This is a thread I'm posting to see what changes people would make to the artificer base class before slotting it in to 2024 DND, if any. Clearly I would make some and I am going to list them out shortly but I am curious if others feel similar or different to me on this. 

Topic One-Subclasses

Firstly I think when considering subclasses for a class one needs to ask oneself what are the main archetypes of this class? In the case of the artificer I see it as Armorer, Alchemist, Construct Designer, and Weapons Smith. Currently we have Armorer, Alchemist, and Construct Designer/Battle Smith. The Artillerist its kind of an odd duck IMO, I like the subclass don't get me wrong but i think i would prefer it as a wizard subclass with an artificer theme. This leaves out a Weapon Smith and IMO this archetype is sorely missed. So on the subject of subclasses I would make sure to add in a new artificer Weapon Smith and move the Artillerist to a wizard full caster subclass. Next I would drastically redesign the alchemist to be a kind of martial(More on this later.)

Topic Two - Spellcasting

Artificers should not be spellcasters, that's right I said it. While I understand the theme of the design I think it is betrayed by its own mechanics. An artificer should be able to cast spells but all of these spells should come from infusions and should need to be built before use. The infusions should be a more robust feature that has all normal dnd magic items removed from its options but instead should give a much wider range of custom infusions that mimic spell effects or give the player access to specific spells a certain number of times per day.

Example:

An infusion called gauntlet/prosthetic arm of shielding, this gauntlet give you access to the shield and absorb elements spell with a total of 4 charges per long rest to cast them with. Perhaps and infusion called ersatz eye/monocle of uncanny sight, this infusion gives you darkvision and see invisibility to a range of 60 feet. (more on this later as well)

This mechanical function of how  optional spells would work on artificers would be closer to how wizards function in that an artificer may not have many spells prepared but the ability to change some of this out during the adventuring day outside of combat enhancing the versatility of this new class methodology while simultaneously deepening the theme that draws people to it. 

Topic Three - Resources

Each subclass has its default item it operates around apart from the alchemist, but even the alchemist requires recourses for their potions. In the case of the non alchemist the resource should be IMO Mithral and Adamantine. Each subclass should have the item from its namesake count as or be adamantine while the other items are all mithral. This would operate as a separate subclass recourse that is compatible with infusions but uses a different recourse (no pun intended).

Example:

The weapon smith would have an adamantine weapon while wearing mitral armor. The armorer should have adamantine armor and use the armor as a weapon. The construct designer/battle smith should have a adamantine construct and be using mithral armor and weapons. 

Normally mithral and adamantine cant be enchanted as they already count as magical, however i think giving the artificer the ability make such items magical should be the representation of the skill artificers have with the crafting of magic items that even the most skilled artisans, wizards, and clerics lack. Furthermore it should be stated that you have to be an artificer to get the extra benefits from their adamantine and mithril magic items. While the mithral and adamantine can be infused only artificers can benefit from infused mithral or adamantine. The mithral and adamantine items should be part of the subclass I think the alchemist should be made into a martial class with more of the throwing or launching of potions, poisons, acids oh my at enemies.

Summation:

The artificer should be a martial class that creates items that have spell like effects or grant the artificer access to certain spells, however this should run completely separate from the classic DnD magic items. The artificer should be a skill monkey with lots of expertise. The artificer should not be able to cast spell unless they are from a magic item or that artificer is multiclassed. Finally the type of material used in the construction of artificer items should be of import. IMO this should take the form of one main adamantine item and the rest as mithral. I like the theme for artificers to be inline with githyanki and mind flayer type psionic devices so I would also like to see basically all of the artificer abilities to add damage to an attack once per turn to be psychic and apply a debuff to those who take damage from that feature. Its the artificers mind that is powerful after all. All in all i think the artificer should fit in as a kind of wizard/rouge/paladin mix in mechanical function as a martial, skill monkey, with some bits of paladin nova flavor in there. 

anyways, do you agree? disagree? I realize this would be a ton of work for WOTC, I still hope the take the artificer in this direction anyways.

To me an Artificer should be more of a modular class like the Warlock invocation with a pinch of the Sorcerers Metamagic flexibility. An example to this is Battlesmith is awesome but the Steel Defender is not customizable which ruin the invention sense of the class. Armorer touch more into it but its limited by the effect of the Infusion since they are based mostly on magic items instead of more individual effects like +1 to AC that grows with lvl in class and the weapon return effect with can easily be subdivided so we can apply more than one as we grow stronger to make items with more unique flavors.

Agreed the core of the artificer class should be creating and upgrading a core item in custom ways to individualize each build, but the magic items they create should be unique and be able to stack together. Maybe not all the time but i feel the core of the class should be creating your own custom version of armor/weapon/construct/potion that doesn't already exist in the game. Artificers should be about innovation and creativity, so let us innovate and be creative with their creations. 

I would really like to see more of a magic item style subclass where there are benefits to planning ahead and putting spells in items that can be handed out to the party. There's really no "tinkerer" subclass which I find really surprising given the way the class is presented. Battle Smith is good but I find it limiting that the only expression of the tinkering is a pet. The infusions are so few and so limited that they play more like feats than like magic tinkering.

I really enjoy playing the Artificer class but you have to really fight with it to make it an inventor/maker instead of half caster using the wizard spell list who can wear armor. That's really fun to play, it's just not what I expected.

YESS thats my real issue with the class! I wanna be an inventor not a half caster with a +1 weapon

People say flavor is free but flavor can be challenging and I have felt I have to actively fight against RAW to add the flavor of a magic tinkerer/inventor. The rules are, I have to have a tool (or infused item) in my hand, not an item I made or an item that I am connected to. The actual infusions are few and not always convenient items for other casting; you certainly don't get one for each spell you might cast. So if by flavor say I want to use a contraption to cast feather fall, I have to have both my contraption AND my tool in hand RAW (and if I'm playing with encumbrance, I also have the weight of all my tools and items). Also means in that case I can't have a weapon or a shield in my hand at that moment unless I've got an infusion on them.

Now if I'm DM I would likely RAI to not worry about the tool-in-hand if you wanted to hold or direct another item and I'd probably also say if you infuse your armor that is your focus even if it's not "in your hand." 

All that said: Very fun class to play, and I've enjoyed stretching and bending the Magical Tinkering into various utility situations. The way that it plays has been very fun for me, it just doesn't function as I expected when I first built the character, and I'm just making my peace with that and embracing the direction the rules take it. Just a little more love and attention facilitating an Inventor/Maker Of Many Things subclass especially at the lower levels and it would be even better.

Well yes flavor is free but I think that the mechanics supporting the flavor first in more important. There are aspects where the flavor of the class but heads with the mechanics, Like you you create a device that spreads a bunch of spiderwebbing that enemies can get caught in, then what is there to concentrate on? where do spell slots come into play with artificers? Same with verbal components and alike? The whole half caster thing just feels like the easy way out of making the class rather then making the mechanics support the fantasy of an inventor. I just think the artificer should create more unique magic items that can stack together and the spells an artificer has prepared are more akin to casting spells from a magic object, in that the spells you choose to prepare each can be cast a number of times per long rest with a shorter list of "prepared spells"

Like flavor IS free but its NO substitute for mechanics that support the fantasy. 

Just how I handle it, but my Battle Smith Artificer studied to become a wizard, but wasn't able to learn to cast his spells without runes or alchemical reagents.  Where others create their spells with just their minds, incantations, and focuses; my Battle Smith Artificer uses a component pouch, alchemical reagents, enchanted paint, runes, and tinker's devices to create his spells and devices.  The method adjusts with the spell, so it might be a device with runes or alchemical reagent on it that activate when magical energies are channeled through it.  For spells that require concentration, I tend to go with either activated runes on devices (rods, wands, or inscribed as part of his armor or weapon) or runes inscribed on paper with enchanted paint that focus the energies (and are consumed in the case of the paper).  In game, I have pushed this further with his taking the ritual caster (wizard) feat.  If I owned Bigby Presents, I would have probably taken the rune carver background also.  

I personally feel that the sub-classes are surprisingly well balanced overall, as each one in their own way slots into the four roles (Warrior, Mage, Priest, Expert).  The Armorer is a beast of a tanking/defender warrior, the alchemist is the healer/support focused, the artillerist is the more like a mage blaster/controller focused, and the battle smith is very much a bard-like pure expert that can be built to fulfill any of those roles. 

However, one thing I have learned with the Steel Defender is that its primary job is in the name, defending.  Basically, every attack against it is an attack that isn't against your party, so dodging and getting in the way is more important than it attacking on a bonus action.  There are times that the attack can help, but most of the time it is more beneficial to have it defend and stay alive to inflict disadvantage on an enemy attack, absorb attacks that would otherwise target someone else, and be the ally 5 feet from the enemy that the rouge is sneak attacking.

You have a lot of really good ideas here. I think some of them don't quite go far enough and others go a little too far, but all in all I think you did a good job summarizing some of the stuff I've been thinking. I'm going to go over the parts I disagree with because I think it's the easiest way to highlight the parts I agree with too.

SPELLCASTING: I believe treating artificers primarily as inventors and tinkerers is core to the class. However, since spells are the primary framework in D&D for interacting with magic, I don't see any around making them anything other than half casters. I do think though that it's possible to greatly shift the focus of their play from spellcasting towards tinkering without taking away their half caster status, by altering their spell list and creating class features that actually integrate their spell casting with their tinkering. Anyone can get tool proficiency and make a lock or a trebuchet or whip up some consumables for the party. I think the artificer's core identity, if we try to ditch the steampunk stuff and sci-fi, is going to be in creating and interacting with magic items to share with the party in a sort-of logistical support capacity. Anyone can fix a wagon, but only the Artificer can make it go without a horse.

SUBCLASSES: The current artificer has 4 subclasses: the Nutty Professor, beastmaster but robot, Escaflowne, and Gun. I don't think this is a great setup. Most of the significant magic item interaction comes all up front when you choose your subclass rather than ongoing choices you make throughout the game.

    I don't think Gun (Artillerist) is a healthy or necessary subclass, it's literally just Eldritch Blast In A Can, but it doesn't fit the theme of a lot of settings and somehow lacks all the customization options of actual Eldritch blast! We can't let warlocks beat us here. You are onto something with the runes binding, where one of the base Artificer class features is binding a cantrip or utility spell to an object. Sorcerers customize spells, Artificers customize stuff. I think the generic "Replicate Magic Item" infusion should be removed from the base class and items split out between the subclasses. There's too many magic items that are strictly better or more useful than your infusions, and too many infusions that are too similar (just a bunch of +1s spread between martial and magical offense and defense)  and to me it makes more sense not to force Artificers to choose between magic items and infusions but put them in 2 separate features: one for customization, and one for creation

   Alchemist I think fulfills an important role, but has too sucks up a little too much functionality that should be built into the base class. Magic consumables should be part of the base class at low levels, with Alchemist as the class to really emphasize them, and really lean into the logistics angle. Most of the consumable items from the old replicate infusion would fall in here: special ammo, potions, one-time use items. Giving them a choice between more ally-based infusions or a more efficient delivery system (sling, bow, whatever) could help fill out the activity.

  Battle Smith's arguably most useful feature, due to it's uniqueness, is it's ability to use Intelligence to attack with magic items. The fact that they have a familiar with a slightly unique statblock doesn't need to take up as much of the subclass identity as it does. I don't think it's meaningfully different enough from other familiar statblocks, especially if the only difference is it's built rather than summoned. Flavor is free, and I don't think the space this feature occupies is worth what it brings. That leaves the core of this subclass being Magically attacking, and without the Artillerist this is the predominantly offensive subclass of the set. That gives us a great direction to go right off the bat: modifying weapons with additional magical and non-magical effects. There's already so many useful spells that can modify weapons, but we agree that treating the Artificer as just a half-caster is boring. This is there the base class feature comes in clutch: we can already bind cantrips to objects to be activated at the appropriate times. Battle-smith uses that on that to allow us to bind weapon buffing and smite-like spell that we set as the subclass spells to allies weapons in our down time. With no other changes, this frees up the Battle-smith to do actual battle during battle instead of having to spend their time casting buff spell. Magic weapons from the Replicate infusion could be granted to this subclass. Could even allow them to spend some class resource or spell slots to refresh those buffs after they expire, or grant allies sword-bond effects like Eldritch Knight has.
  Armor's current role of "you're in a mecha" is not super thematic, and the fact that you really only get 2 options for customization with it that don't have a way of interacting with the other items you're customizing means you don't really get to tinker or interact much once you pick a setup you like. It does have some interaction with your infusions, but only in that it absorbs them and prevents you from using them to interact with the rest of the team. Plus aside from the magic items, the base infusions really don't allow for much creativity in how they're applied to the armor. It feels like a waste to make this as an armor-based copy of Battle Smith, where you just stick some defensive spells onto armor and let your allies activate them at will. I think this is a perfect candidate to be replaced by your Rune Knight, where instead of binding spells to things it has its own semi-unique set of persistent effects that you and your allies can use. The fact we're not limited to spells means we can really fine-tune the balance on them in terms of quantity vs power moreso than we could using just spell slots and levels. We can still use the spell slots as a resource to power effects from the runes themselves (For example: a rune that lets you expend a spell slot to blind every hostile creature in a radius around the rune equal to the level of the slot times 5ft, or spend a slot to double the bonus it provides for a length of time), or let you certain spells with their origin point as the location of the rune. It allows you to use the half-caster part of the class in direct conjunction with the subclass features, while not forcing you into just feeling like half-a-wizard. Lots of the wondrous items would fit here too, lots of boots and cloaks and amulets.
  I'm not exactly sure what a good 4th subclass would be. I think Shields are underused items that don't really fit into any of the previous themes. There's lots of interesting abilities that fit with them. You could fortify allies to respond with magical effects when they get attacked (a good use for the cantrip infusion ability from base class). You could dump magic power into the shield to provide cover to nearby allies or create semi-permanent cover. Casting spells with a range of Self from both your location and the location of an ally with one the infusions from the base class. Powering some Aura-based buffs/debuffs could be fun, or increasing the number of creatures you can target with a spell if they're close enough to you. The fact that a shield is your central feature also means that you could give them free access to some of the defensive fighting style feats, since the existing martial classes that have access to them don't often build as Supports.

One thing I really agree that base-class is missing is the ability to interact with existing magic items, or providing buffs to allies that have magic items better than yours. Giving the base infusions level scaling instead of quantity-scaling would make it so that so many of the earlier infusions won't be useless once party members get other magic items. For example: you can give a item +1 right away, but making it into a flat bonus with a scaling limit means by the time all your allies have their own +1 versions of their relevant items, you can now make one of them a +2. Lots of magic items with charges that replenish themselves have a chance to permanently lose their magic every time you drain their charges down to 0. I'd love for artificer to be able to intervene with a saving throw when that happens. Being able to NEGATE the effects of magic items would also provide a lot of utility. De-cursing, suppressing buffs, countering spells cast by items, destroying enemy's spell scrolls. There's almost so many options for Artificers it makes it hard to create a coherent class. I think your rune suggestion solved a thing I'd been thinking about for a long time, where instead of the subclasses being about WHAT the artificer makes, they could be about HOW they make it. Alchemy, Runes, spell-infusion, active magic conduits, they all provide very fun and different themes to build around without restricting functionality, unlike the current subclasses where it feels like the theme is solely defined by their unique item.

I've been theorycrafting with Artillerist a bit lately, and I think although it's advertised as "Gun," Artillerist is possibly much more flexible in actual play than the name suggests. I'm thinking it could make a pretty interesting Doctor if you tune the Eldrich Cannon to spew hit points in its Protector mode especially if you add a Homunculus as one of its infused items. The further I get along in play and the more I experiment, the more I find unexpected synergies in features that give me delight.

I could see revisiting the spell list to ensure anything involved could be plausibly flavored into being a magical device, or something along those lines, but most of them can be flavored into that reasonably well (my Artificer's use of Shield is a deflector shield projector built into the back of his gloves, and his uses of Aid are adding some extra bits of armor to himself and/or allies, and Haste is him firing an injection needle of adrenaline into someone, levitation would be the activation of a magical gyroscope gizmo on his belt, etc.) Not crazy about the thematics of some of the concentration spells, though- there's no reason that something based on an "injection" into someone else should be affected by you getting hit, or the a static lingering effect of a "prejectile" (eg. Web) would be affected by you getting hit.

What is definitely needed are some abilities to make spells like Magic Weapon and Elemental Weapon useful at the levels they're obtained, like the ability to apply them to either magic weapons or weapons that you've infused. Along the same lines, the artificer should eventually be able to infuse magic weapons and armor.

I do like the idea to add more customization to things like the Steel Defender, Armorist's armor, and the Artillerist's cannon- increased movement speed, higher HP or AC, more attack potency, ability to attuneme and use magic items, other random abilities, etc. They need better scaling, and customizing that scaling would be a nice option to have.

And depending on the new crafting rules, the level 10 feature could probably be trickled in a bit earlier, say, by level 6, to cut the crafting cost by 10% and the crafting time by 25%, at least. There's no reason that, as someone who can casually and immediately (or within 24 hours) infuse a common weapon into being something along the lines of an uncommon weapon, I shouldn't be able to, using a +1 sword and a red dragon tooth or something, create a flametongue sword in less than 320 hours (enough downtime for an entire tier of play to have passed).