Inventor Handbook: PF2 Class Guide

Introduction

The Inventor’s features center around your character’s Innovation, which is equal parts equipment and subclass, greatly influencing your tactics and your role in the party. Depending on your choices, your Inventor can be some combination of Defender, Scholar, Scout, and Striker.

The Inventor is a curious martial-adjacent character, falling into a role in the party similar to the Fighter but leaning slightly toward the Rogue. With high Intelligence you’ll start with abundant skills and you’re well suited to crafting items of various types.

The Inventor has a lot of decision points for a non-caster, making them complex to build and play. It can also reward deep understanding of PF2’s crafting system. Weirdly, the Inventor also does a great job of making complexity “opt in”, allowing you to choose between options which aren’t strictly better or worse but which might be more or less complex to build and play. In Pathfinder 2e where building any character is complicated, this is refreshing.

I also recommend out Inventor Innovations Breakdown for help selecting your Innovation and your Modifications.

Disclaimer

RPGBOT uses the color coding scheme which has become common among Pathfinder build handbooks.

Red: Bad, useless options, or options which are extremely situational. Nearly never useful.
Orange: OK options, or useful options that only apply in rare circumstances. Useful sometimes.
Green: Good options. Useful often.
Blue: Fantastic options, often essential to the function of your character. Useful very frequently.

Inventor Class Features

Key Ability: Intelligence. With high Intelligence you’ll start with numerous trained skills and you’ll be effective with Crafting, which is great because you need to succeed at Crafting checks to use some of your class features.

Hit Points: 8+ hit points. This is plenty for artificers who plan to fight at range, but if you’re planning to fight in melee you need to be cautious. Your armor and hit points aren’t as good as classes the like the Barbarian, the Championm, and the Fighter,

Initial Proficiencies: Trained in simple weapons, martial weapons, and up to medium armor (heavy if you select the Armor innovation). Your AC isn’t going to be amazing and you’re not going to be amazing at attacks, either.

Perception: The worst progression in the game. Don’t dump Wisdom, and strongly consider using a skill for Initiative if possible.
Saving Throws: Expert in Fort and Will to start, but you don’t adance to Master until higher level than most classes. The Inventor’s Reflex saves are among the worst in the game.
Skills: A total of 4+Int Trained skills from your class, and since Intelligence is the Inventor’s Key Ability Score you should start with a bunch of skills. You’ll advance in Crafting for free, too, so you have a slight edge over other other classes with similar starting skill proficiencies.
Attacks: Simple and Martial weapons, and your proficiency advances at the same rate as martial classes like the Barbarian and the Ranger.
Defenses: Medium armor and a similar proficiency progression to other martial classes.
Class DC: The Inventor’s Class DC is used for weapon critical specialization effects (though you only get those with the Weaopon innovation by default), for the Explode activity, and for a handful of Inventor Class Feats like Megavolt. The Inventor’s Class DC follows the best progression in the game.

Overdrive: A small but meaningful damage boost. The Action cost is small, but can still be somewhat annoying since you likely want to use this in every fight. Note that this requires a Crafting check and the DC will increase as you gain level. Fortunately, you get improvements to Overdrive at levels 3, 7, and 15, each of which also increase your proficiency in Crafting for free so you don’t have to worry about it too much.

Overdrive can be re-activate while it’s still running, potentially allowing you to raise a Success to a Critical Success to get the larger damage bonus. In most cases this isn’t worth the Action, but maybe you don’t have anything better to do.

Innovations: See our Inventor Innovations Breakdown.

Explode: The damage is decent, the scaling AOE is nice, and triggering Unstable generally isn’t all that bad since it doesn’t prevent the item from working. Unstable is only a one in five chance to not malfunction, so don’t expect to use this more than once per combat.

Peerless Inventor: You gain the confusingly-named Inventory skill feat (confusing because it’s also your Class’s name, so searching for it is hard) long before you could reach Master proficiency. If you’re going to depend heavily on crafted items, formulas are going to be important, and you don’t want them to become a massive money sink. Instead, the Inventor feat can become a time sink.

Shield Block: A significant boost to your durability if you can spare a hand and an Action for a shield. So long as your Innovation isn’t a 2-handed weapon, you’ll at least have a free hand. If you’re going for Armor or Construct, that’s easy. If you’re going for Weapon, either go for something one-handed or fight at range.

Inventor Feats: See Inventor feats, below.

Skill Feats: Standard for everyone except the Rogue.

Expert Overdrive: One more damage with Overdrive and Expert in Crafting. You get a Skill Increase at the same level, which means that you can be Expert in two skills right at level 3.

General Feats: Standard.

Reconfigure: The Inventor’s class mechanics are unique, so their retraining mechanics need to be unique, too. The fact that this requires a Crafting check is really odd, and the fact that it’s a high DC means that you’re expected to fail sometimes. If you’re going to retrain things, make sure that you have a few days to spare in case you mess it up.

Skill Increases: Standard for everyone except the Rogue.

Ability Boosts: Standard.

Ancestry Feats: Standard.

Inventor Weapon Expertise: More weapon proficiency and you get access to Critical Specialization Effects with your innovation if you chose the Weapon innovation.

Breakthrough Innovation: See our Inventor Innovations Breakdown.

Lightning Reflexes: Your Reflex save proficiency is bad, so you need as much help as you can get.

Master Overdrive: Another +1 damage when you Overdrive, and Master in Crafting. That’s not a huge improvement at this level, but it’s hard to say “no” to more damage from something that you should be doing anyway. At this level your Intelligence modifier is likely +4, so you’re gaining +4 damage from a successful Overdrive and +6 from a Critical Success.

Weapon Specialization: Couple with the Overdrive feature, you can deal quite a bit of damage with your Strikes. Inventors with the Construct Innovation will benefit less.

Inventive Expertise: Improving your class DC means a higher save DC for things like Explode.

Offensive Boost: 1d6 damage isn’t huge, but it’s as much damage as a property rune like Flaming and it doesn’t cost anything or consume a rune slot.

Medium Armor Expertise: More AC and access to critical specialization effects if you have the Armor innovation. I think the rules are supposed to say “armor specialization effects”, but they do say “critical specialization effects”, which definitely isn’t a thing for armor. Since the armor options are both Composite, that means resistance to piercing damage.

Resolve: Better Will saves. You’re still advancing very slowly, but we’ll take what we can get.

Alertness: Horrifyingly late.

Complete Reconfiguration: This allows you to retrain huge portions of your build in a hurry. Do this cautiously or you may find that other portions of your build stop working.

Inventor Weapon Mastery: More attack bonus.

Greater Weapon Specialization: More damage is always nice.

Legendary Overdrive: Yet another +1 increase to your Overdrive damage. That feels really small at this level, but by now you likely also have a +5 Intelligence modifier, so you’re gaining +5 damage from a successful Overdrive and +8 from a Critical Success.

Revolutionary Innovation: See our Inventory Innovations Breakdown.

Inventive Mastery: More class DC is always great.

Juggernaut: More saves are always nice, and Fortitude is likely your best save.

Infinite Invention: This allows you to change huge portions of your build during your daily preparations. The concept is neat, but the practical implications are worrying. You’ve almost certainly built huge portions of your character around your innovation, so changing your innovation and all of its modifications is both a ton of bookkeeping and a potentially ruinous change to your build. But at the same time, you also gain a ton of flexibility to customize your innovation to suit challenges that you expect to face. Use this cautiously.

Medium Armor Mastery: More AC.

Ability Scores

The Inventor is surprisingly MAD, even for Pathfinder 2e. You need Intelligence to support your class features and skills, but you’re also sort of a martial class so you need some combination of Strength, Dexterity, and Constitution. Your Will saves are poor, so you also need Wisdom. That leaves Charisma as a dump stat, but you’re going to have to weigh your other decisions based on your other build decisions.

Str: If you’re using a Strength-based weapon (most melee weapons), you need all that you can get. If you’re using a finesse weapon or a propulsion weapon you need a little bit for damage. If you’re using a crossbow or a firearm or if you select the Construct innovation, you may be able to dump Strength.

Dex: Inventors get medium armor proficiency, so you likely need 12 at minimum. If you choose the Armor innovation and choose the Subterfuge Suit or if you’re using a finesse weapon or a ranged weapon, you need more Dexterity than you would otherwise.

Con: Hit points and Fortitude saves. This is especially important if you plan to be in melee because you only have 8+ hit points and medium armor.

Int: Your Key Ability Score. Regardless of your other build decisions, this is absolutely crucial.

Wis: You need a bit to support your poor Perception and Will saves, but how much you can afford will depend on your other build choices.

Cha: Dump.

Ancestries

Because the Inventor is somewhat MAD, three Boosts can be very helpful. Access to an Uncommon weapon can be great for the Weapon Innovation because you can often start with better weapon properties than you could with Common weapons. Ancestries which offer access to better unarmed strikes may be appealing for Armor Innovation, though remember that the Armor Innovation does still let you improve a regular weapon with things like Offensive Boost, so it’s not absolutely necessary. Damage resistances to common damage types (fire, etc.) can also be helpful. For Construct Innovation, consider options related to skills, new support options, and potentially spellcasting if you can get utility and support spells.

Catfolk^APG: The Boosts/Flaws are hard and the feats don’t help much. You could use the Optional Flaw rules to dump Charisma to end up with three Boosts and Flaws in Wisdom and Charisma, but the Catfolk’s Ancestry Feats don’t offer anything especially helpful for the Inventor. The Cat’s Luck feat tree is always good, but that’s just not enough on its own.

Dwarf^CRB: No Strength/Dexterity boost, so you’ll need to use the Optional Flaw rules to get boosts to both Intleligence and either Strength/Dexterity, and since the Dwarf’s Flaw is already in Charisma you’ll likely need to put the additional flaws in Wisdom and either Strength or Dexterity, giving you three boosts and three flaws. That’s already a hard prospect since the Inventor is unusually MAD, and for your trouble you’ll likely find that the Dwarf’s Ancestry Feats do little to support the Inventor.

Elf^CRB: Boosts to Dexterity and Constitution, but a flaw in Constitution is hard if you want to go into melee. If you want to fight at range, grab a bow and consider the Elven Longevity feat chain to emphasize your skill capabilities. If you want to fight in melee, use the Optional Flaw rules, put the new flaws into Wisdom and Charisma, put both of your free Boosts into Constitution, and grab the Toughness feat to compensate for your 6 hit points from your Ancestry Strongly consider the Elven Curve Blade, which will require the Elven Weapon Familiarity feat. But if you’re going to go to all of that trouble, consider a human with the Unconventional Weaponry feat.

Gnome^CRB: Starting from a Boost to Charisma (our dump stat) and a Flaw in Strength is a hard starting point. You can use the Optional Flaw rules to dump Charisma for another Free Boost to get boosts in Dex, Con, and Int. If you’re going for the Weapon Innovation, strongly consider the Gnome Weapon Familiarity feat for access to the Gnome Flickmace or the Gnome Hookhammer. Of course, at that point a human with Unconventional Weaponry might be easier. The Gnome’s Ancestry Feats do little to directly complement the Inventor, but Animal Accomplice might be helpful.

Goblin^CRB: A startlingly large number of options for the Inventor. The Boosts/Flaws aren’t great, so use the Optional Flaw rules to dump Charisma for another Free Boost to get boosts in Str/Dex/Int or Dex/Con/Int. The Charhide Heritage is great for mitigating self-inflicted fire damage when you critically fail with a handful of Inventor features and feats. The Razortooth Heritage gives you a bite attack which can be a helpful weapon option if you chose the Armorer Innovation. Goblin Weapon Familiarity appeals to Weapon Innovation, and any Inventor can use City Scavenger and Junk Tinker.

Halfling^CRB: A good option for Dexterity-based Weapon Innovation builds. Halfling Weapon Familiarity offers access to the Filcher’s Fork and the Halfling Sling Staff, both of which are great options for adding additional modifications. The Halfling’s Strength flaw may be a problem, so consider the Optional Flaw rules to dump Charisma and put boosts into Strength. The Halfling Luck feats are always good, but there are few other feat options which are obviously good choices.

Human^CRB: A great basis for many builds. Natural Ambition and Multitalented are great on basically any character. Unconventional Weaponry is great if you want to pursue the Weapon Innovation, but the Human is consistently a good choice for any variety of Inventor. The Half-Orc heritage’s access to Orc feats is appealing for options like Iron Fists and Bloody Blows which can make unarmed strikes a viable option if you choose the Armor Innovation.

Kobold^APG: Use the Optional Flaw rules to turn the Charisma Boost into a Flaw, then use the three boosts to increase you Dexterity, Constitution (negate the Con flaw), and Intelligence. This gives you a good basis for a Dexterity-based build, and with the Kobold’s Ancestry Feats you could do some interesting things with snares by taking the Snarecrafter archetype.

Orc^APG: Good for Strength-based melee builds. Armor Innovation needs a good attack option, and the Orc’s Iron Fists and Bloody Blows feats may do the trick. For Weapon Innovation, Orc Weapon Familiarity gets you access to the Orc Necksplitter, which is an upgrade from the Battle Axe.

Ratfolk^APG: The Ratfolk’s Boosts and Flaws are perfect for a Dexterity-based build, but their Ancestry Feats do little for the Inventor. Consider the Adopted Ancestry feat. Otherwise, your best bet is to lean into the cheek pouches concept and craft a bunch of items.

Tengu^APG: Only two Boosts, but you could use the Optional Flaw rules to get a third. Even then, there’s not a lot here worth having. Tengu Weapon Familiarity gets you access to the Tengu Gale Blade, but it’s a shortsword with the Disarm trait, which isn’t enough of an improvement to justify a feat unless you’re expecting to Disarm most of your opponents.

Backgrounds

You need a boost to Intelligence. Inventors planning to rely on making their own Strikes will also need a boost to Strength or Dexterity depending on your build. If you choose the Construct Innovation, you can do without a Strength/Dexterity boost and put that boost somewhere else.

If you’re having trouble deciding, here are some suggestions:

Artisan (Strength-baed build)
Artist or Tinker (Dex-based build)
Hermit (good for knowledge skills)

Skills and Skill Feats

You get Skill Increases at 3rd and 5th level to raise skills to Expert, increases at 7th, 9th, 11th, and 13th level to raise skills to Master, and increases at 15th, 17th, and 19th level to raise skills to Legendary. That means that you can maximize at most three skills, and the rest of your skills might not advance beyond Trained.

You get Skill Feats at even-numbered levels, giving you a total of 10 Skill Feats (and maybe another from your Background) by 20th level. Generally, you want to invest these feats in the same skills which you are choosing to maximize, though in some cases you may want to grab feats from skills which don’t require that you be more than Trained.

Acrobatics (Dex): Only situationally useful. Unless you plan to fly frequently, this will rarely matter.
Arcana (Int): A great secondary use for your high Intelligence.
Athletics (Str): Armor Innovation offers access to an easy Athletics bonus and Weapon Innovation offers many ways to make Shove and Trip effective.
Crafting (Int): The Inventor’s most important skill. You’ll use it for some of your class features (Overdrive, mostly) and for making and repairing items. Fortunately, you also advance your Proficiency in Crafting for free as early as possible so it’s not a tax imposed on your build decisions.
- Inventor^CRB: You get it for free long before anyone else can.
- Magical Crafting^CRB: A great way to save yourself and your party a ton of gold and also get better gear.
Deception (Cha): Charisma is the Inventor’s only easy dump stat.
Diplomacy (Cha): Charisma is the Inventor’s only easy dump stat.
Intimidation (Cha): Charisma is the Inventor’s only easy dump stat.
Lore (Int): Too situational and too specific.
Medicine (Wis): Make someone else in your party handle this. With your emphasis on crafting you should be spending your time after encounters repairing everyone’s equipment.
Nature (Wis): An important knowledge skill. You can likely afford to be at least trained.
Occultism (Int): A great secondary use for your high Intelligence.
Performance (Cha): Charisma is the Inventor’s only easy dump stat.
Religion (Wis): An important knowledge skill. You can likely afford to be at least trained.
Society (Int): The closest thing you should get to a social skill.
Stealth (Dex): A great choice if you’re building around the Subterfuge suit.
Survival (Wis): too situational.
Thievery (Dex): A great choice if you’re building around the Subterfuge suit.

General Skill Feats

Recognize Spell^CRB: You have the Intelligence to back up Arcana and Occultism and you hopefully didn’t dump Wisdom, so being Trained in all four and taking Recognize Spell is an inexpensive way to get a lot of information for your party.

Feats

Inventor Feats

1st Level

Built-In Tools^GG: Why yes, I would love to put 2 Bulk worth of tools into my dagger nonmagically. This is basically only useful if Bulk is a huge problem for you and you still need these tools available in combat. The rules for wearing tools specify a bulk limit of two, so this fully doubles that capacity. It’s only useful if you’re building around stuff that requires tools in combat.
Explosive Leap^GG: Only situationally useful.
Haphazard Repair^GG: This is great for Construct, but probably not worthwhile for other Innovations since armor and weapons don’t take damage in combat as frequently as a creature. Remember that this is unstable, so you’ll making a DC 17 Flat Check after you use this, so you’ll likely only be able to use it once per combat. Expect to retrain this at high levels when Quick Repair makes repairing items much faster.
No! No! I Created You!^GG: Very situational, but your companion’s saves are weak so anything that can confuse or charm things probably sees your companion as an easy target.
Prototype Companion^GG: While not so effective as the actual Construct Innovation, this does get you a construct companion which then qualifies you for many feats intended for inventors with Construct Innovation. Of course, it’s a very feat-heavy choice choice to build around the construct companion, so it may not be worth the feats unless you’re taking Construct Innovation. You might take this just to get a mount, but an animal companion may be a better choice if you don’t mind taking an archetype. Note that companions gained from this feat follow the normal Minion rules, so you can’t spend two Actions to command this companion and give it three Actions.
Weirdly, selecting Construct Innovation doesn’t give you this feat (you go straight to getting the companion), so you’re free to select it to get a second companion. I have no idea how that interacts with the feats that advance your companion, but I assume that the answer is that you pick one companion to advance while the other remains a prototype.
Tamper^GG: The Critical Success effect is really good, but otherwise this isn’t worth the Action, so it’s only worthwhile to use this on enemies with poor Reflex DC’s. Even then, the risk of damaging yourself on a Critical Failure seems unnecessarily punishing.
Variable Core^GG: Fire resistance is common, which reduces the effectiveness of Explode. If you rely on Explode offensively, switching your damage type to acid or electricity can be very helpful. If you have damage resistance to one of the listed energy types, you might use this to mitigate the risk from certain Inventor features and Class Feats. Of course, those things generally deal fire damage and resistance to fire damage is available from several Ancestries, so sticking to fire is less costly unless you also want Explode to deal a different type of damage.

2nd Level

Collapse Armor^GG: I can’t think of a situation in which you would want to remove your signature class feature that’s common enough to justify investing a feat to do it.
Collapse Construct^GG: Novel, but almost no impact on the game.
Reverse Engineer^GG: The crafting thing is neat, but the real value here is using Craft in place of Thievery for Thievery’s two most important uses. If your party doesn’t have a rogue or someone to replace one, this is worth considering.
Searing Restoration^GG: For a single Action this surprisingly good healing. But it’s also an Unstable action, so you likely won’t be able to use this or other Unstable actions again until you have time to repair, so you can only expect to use this once per encounter. Consider taking the Medicine skill and the Battle Medicine skill feat instead.

4th Level

Advanced Construct Companion^GG: Essential if you selected the Construct Innovation.
Diving Armor^GG: Only useful if you’re planning to go underwater. Fortunately, it’s a Modification feat, so you can retrain it easily for another Modification feat.
Dual-Form Weapon^GG: “Any runes on your weapon innovation don’t affect the second weapon configuration.” This becomes a liability the moment you can afford weapon runes.
Gadget Specialist^GG: An easy go-to option for nearly any Inventor. Gadgets include a variety of utility items, as well as combat options like ablative armor and explosive mines. However, gadgets can’t compete with the diversity and utility of Advanced Alchemy, so you may be better served by taking the Alchemist multiclass feats. Despite getting items of a lower level you’ll get considerably more of them (one per character level rather than 2 to 8 depending on your feat choices) and your options will be much more diverse. The alchemical items in the Core Rulebook alone vastly outnumber the gadgets printed in Guns and Gears, and we’ve since recieve a huge number of additional alchemical items in other supplements including Guns and Gears.
Megaton Strike^GG: An easy go-to option, but you want the biggest damage die possible to make this matter. Ideally 1d10 or larger. For small damage dice you’ll get more benefit out of making multiple strikes to apply other damage bonuses from ability scores, runes, etc.

6th Level

Clockwork Celerity^GG: This is an Unstbale Action so you’re unlikely to use it more than once per combat, but it’s still a free Action once per encounter. Normally that takes a high-level feat like Quicken Spell which isn’t available until above 10th level. If you don’t plan to use Explode (maybe you’re fighting at long range), this is a great choicef or your favorite Unstable Action.
Construct Shell^GG: If you’re going to ride your Construct Companion, this is essential. You probably don’t need to ride your companion, but it’s an option.
Megavolt^GG: It’s hard to line up more than two creatures with a line effect regardless of the its length, but this does provide an inexpensive multi-target damage option and the damage scales automatically so it can easily outdo your Construct Companion’s Strike damage. If you need to hit more than two targets, use Explode. The Unstable Function is tempting because it roughly triples the damage, but that will rarely be a better choice than Explosion.
Visual Fidelity^GG: Low-light vision, Darkvision, and you can spot invisible creatures. This is really good, and if your Ancestry doesn’t provide better than regular vision it’s even better.

8th Level

Gigaton Strike^GG: Just use a Shove weapon. Investing a second feat into one Unstable Action that then requires an attack and allows a save is a horrible investment.
Incredible Construct Companion^GG: Essential if you selected the Construct Innovation.
Manifold Modifications^GG: Good but not essential. There aren’t many amazing Modification options in the initial set for any one Innovcation.
Overdrive Ally^GG: Rarely worth the Action cost, and the fact that your target doesn’t benefit from the scaling damage bonus is a frustrating and pointless limitation.
Ubiquitous Gadgets^GG: Two more gadgets gives you a lot of options, especially by this level when you can start making improved versions of many gadgets.

10th Level

Distracting Explosion^GG: Only situationally useful. Many creatures don’t have actions with the Concentrate trait. Unless you expect to be in melee with a lot of spellcasters you’ll get limited benefit from this.
Electrify Armor^GG: Even with the Unstable Function the damage isn’t great unless you’re planning to take numerous small hits and somehow not die with your 8+ hit points.
Helpful Tinkering^GG: The benefit is good and the Action cost is cheap, but with a High DC you can’t guarantee Success so it’s a frustrating gamble, especially since you could hurt an ally and you can only use this once every 10 minutes.
Lock On^GG: A great option for using your last remaining Action after spending two to Command your Construct Companion. The bonus is surprisingly large, too. Consider combining this with Megaton Strike since the bonus only applies for one attack.

12th Level

Boost Modulation^GG: Not always useful, but the ability to switch between three damage types can be a good way to capitalize on enemy vulnerabilities or to avoid resistances.
Contingency Gadget^GG: Many gadgets are only situationally useful, so it’s hard to justify using one of your few free gadgets to bring them along. This removes that opportunity cost.
Deep Freeze^GG: The damage is terrible and the duration of the effect is too short. The cone option is tempting, but even then the duration of the effect is too short unless you can catch a huge number of creatures in the area of effect.
Gigavolt^GG: “it bounces off at an angle of your choice.” This makes it much easier to catch more than two creatures in your line, and even if you’re not using the Unstable Function of Megavolt, you can often use this in close quarters to hit additional foes without needing your Construct Companion to move.
Shared Overdrive^GG: A great support option if you have an ally who relies of making numerous strikes, but be very thoughtful about spending two feats to get this unless you’re certian that you will use it in every combat encounter.

14th Level

Explosive Maneuver^GG: The Inventor can be very effective with combat maneuvers, and this makes it much easier to fit them into a turn without worry about your Multiple Attack Penalty.
Paragon Companion^GG: Essential if you chose the Construct Innovation.
Soaring Armor^GG: Astoundingly good. You do still need to follow all the rules for flight (spend 1 Action to Fly each turn or fall), but there’s no limited duration and you don’t have to cast a spell.
Unstable Redundancies^GG: Unstable Actions are among the Inventor’s best options, but you can typically only use them once per combat encounter. This allows you to do it twice.

16th Level

Just the Thing!^GG: Once per hour, provided that you can imagine and verbally describe an object which would be helpful, you can use your Crafting skill for any skill. Considering that Crafting is likely your best skill, that’s fantastic. Consider diversifying your skill proficiencies to unlock Trained Actions for numerous skills to expand how useful this is.
Persistent Boost^GG: A decent amount of damage with no additional check or save or antything. You just need to hit. Spread this around early in an encounter and watch the damage add up in a hurry.
You Failed to Account For… This!^GG: You can do this every round. Your Crafting DC is almost certain to exceed your AC (maybe if you chose the Armor Innovation your AC is a bit better) so this is a significant improvement to your durability.

18th Level

Devastating Weaponry^GG: Every enemy within 30 feet will include every enemy in most encounters. If you have Persistent Boost this will also apply persistent damage to everything you hit, allowing you to apply persistent damage to every enemy in an encounter within a single turn. Tragically this won’t work for crossbows or firearms, but for everyone else it’s amazing.
Engine of Destruction^GG: Basically the same thing as Devastating Weaponry, but your Construct Companion gets to Stride before using it and gets a +2 Circumstance bonus to the Strikes. Your companion’s attack bonus won’t be as good as an Inventor of your level using their own weapon, so he additional bonus is great.
Negate Damage^GG: This competes for space with “You forgot to account for… This!”. This is great, of course, but it’s a choice between a chance to negate a hit and a choice to reduce the damage by 15 (50 if you use the Unstable Function).

20th Level

Full Automation^GG: A free Action each turn. Literally always good.
Ubiquitous Overdrive^GG: By this level you likely have 22 Intelligence, so you’re looking at a +6 damage bonus for your whole party.

General Feats

Canny Accumen^CRB: The Inventor’s Perception doesn’t advance to Expert until level 13, and never advances any further, which means that from levels 1 through 12 and from 17 to 20 this will improve your Perception. Considering that’s 80% of the level range, that’s pretty good.
Toughness^CRB: If you’re building for melee you should strongly consider this. 8+ hit points and medium armor is not enough to pretend to be a fighter.

Weapons

With damage boosts from both Overdrive and from Offensive Boost, the Inventor is incentivized to make numerous small hits rather than a few large ones. That means that the action cost to reload weapons like crossbows can be a problem. Strongly consider Agile weapons, especially since it’s one of the few traits that the Weapon Innovation can’t get you. For ranged weapons, bows are the natural choice, but you may also find thrown weapons to be very effective with some modifications and runes.

Shortbow: The damage die isn’t amazing, but with the damage boosts from your class features that will be less of a problem. Strongly consider upgrading to Compose for the Propulsion property if you have the Strength to make that matter.
Shortsword: Agile, versatile, and one-handed so you can use a shield. This is an easy go-to option for melee builds.

Armor

Explorer’s Clothing^CRB: If you’re building around Dexterity, this is where you want to end up at level 15 when you can get your Dexterity to 20. Light bulk and no check penalty.
Leather^CRB: If you’re building around Dexterity, this is where you want to end up at level 5 when you can get your Dexterity to 18. Once you hit 20, swap for Explorer’s Clothing to lose the Check Penalty.
Studded Leather^CRB: Since Dexterity isn’t your Key Ability Score, you can’t get it to 1 at level 1. If you’re going for a high-Dexterity build, you likely want to start with 16 Dexterity and Studded Leather, then swap for Leather when you hit level 5 and put another Boost into Dexterity. The only thing to worry about is the Strength requirement.
Breastplate^CRB: The logical choice for Strength-based artificers and for anyone relying on their Construct Companion.

Archetypes

Alchemist^CRB: A natural choice for a character built around the Crafting skill. Bombs likely won’t help you, but inexpensive access to mutagens and other alchemical items can be hugely helpful.
Gunslinger^CRB: The 10th-level feat offers access to a special reload Action which can mitigate some of the action cost to reload a firearm or a crossbow, but two Class Feats to make a crossbow as good as a bow is extremely expensive for very little benefit so you need to find some other benefits here.
Wizard^CRB: You’re already Intelligence-based, so multiclassing into Wizard isn’t a huge stretch. Pick up some support options and you could buff your Construct Companion.
Snarecrafter^APG: Similar to Advanced Alchemy, Snares are an easy way for the Inventor to expand their capabilities related to Crafting. Inventors also get a lot of options to be very good at Shove, so dropping a snare and shoving enemies into it may prove effective.

Inventor Handbook: PF2 Class Guide – RPGBOT