I really, really, really don't like that they're trying to fit mechanical engineering into a spellcasting chassis.
Personally, I love it. I think it suits what they're trying to accomplish perfectly. I'm all for having multiple ways for magic to happen.
It gets worse as it goes on, and the whole time I'm wondering... why? Why not just give the Artificer their own unique abilities that allow them to manufacture mechanical spiders that bind wounds or produce healing salves? Why make these abilities "spells" and dump all the responsibility of making them cool and flavorful onto the players themselves? Also, what happens when the Artificer enters an anti-magic zone? Do the clockwork spiders suddenly stop working? Or the healing salves? Meh...
I wish they'd just make an all-out engineer class (with gunpowder and clockwork inventions a la World of Warcraft) or an all-out magic-item-creation class. Instead, they're trying to kill two birds with one stone and fit both archetypes into a single class. It just doesn't work.
Because, from a game design perspective, you're asking for new mechanical game systems for things that don't actually need new mechanical game systems. Balance-wise, spells are a known commodity including how they work with multiclassing. You'll either end up designing something that looks like bad spells that don't scale right because you had to oversimplify the system (e.g., Battlemaster dice) or you're essentially completely re-implementing the entire magic system with the same underlying balancing rules except it has to look like that's
not exactly what you've done. It's much easier to just reuse the existing design. It not only saves you the considerable hassle of building two competing game systems that have to be balanced against each other, you also don't have to teach your players a new system from scratch and you don't have to worry that what you're doing is going to work great at one table and completely break down at another. That's why the answer the designers go to is almost always "give it spells and magic." Further, one of the 5e philosophies is to try to keep the rules as simple as practicable. That also pushes design towards re-use of spellcasting and magic and the mechanics.
Second of all, people want
a class that can build magic items. That's absolutely core to the class concept of an Artifacer. It's what people asked for in 3e, and it's what that Eberron's Artifacer did. It's like the Paladin's Smite Evil or the Bard's music or the Wizard's signature spells or the Rogue's sneak attack. Artifacers make magic items.
So, not only is it extremely difficult to do what you're asking, what people are expecting the class to do pretty much requires magic. So, they tell you to use magic, and use spells, but to come up with thematic and narrative components to how your stuff works. Going to cast
web? Well, you pull out a glue gun and fire it. The same gun also has a
grease mode. Casting
expeditious retreat? Rocket skates.
Cure wounds? Hypospray.
Wall of stone? Instant concrete grenade. Why do you have limited uses? Because the devices are roughly made, slipshod, one-off, hand-crafted, cobbled together prototypes. Just because you're a genius doesn't mean your tools have the precision required for them to work reliably --
in the field no less! They require a lot of maintenance to keep working, and it's exhausting to do it. And, yes, they may of the effects use magic combined with technology to create the result.
Couple of things jump out.
1. Being able to spend a bonus action to have your homonculus perform the Help action kinda steps on the Mastermind's toes a bit. But, it is pretty cool. And, it makes the pet VERY useful without needing to have a "combat pet".
Eh, I don't think preserving the uniqueness of one ability of one subclass is particularly valuable. Particularly when the Homunculus is going to have to expose itself to combat if it wants to help in combat.
2. I get the notion, but, a turret isn't really a pet is it?
It is now. It made me think of the engineer from Team Fortress 2. I dig it. Realistically, you could call it a golem or construct if the name "turret" bothers you. It moves so slowly and lasts such a short amount of time, it's not going to be around very long.
3. Why does this class get extra attacks per round? I mean, the spell list for both subclasses is pretty robust - they've got damage spells down pat. None of the other casters get multiple attacks as a baseline. Seems a tad unnecessary to me. And, unless you pick up a magic weapon, doesn't that make the Enhanced Weapon infusion pretty much a must have? Additionally, I know that my current DM had a real issue with my forge priest getting a magic weapon at 1st level, I can't imagine he's going to be thrilled with someone who can create two magic weapons at 2nd level and give them to anyone.
100% because it's a half-caster. Note that the class gets a pretty beefy selection of armors. This class, like Bard and (to some degree) Cleric, gets to choose whether they want to be spell-based or weapon-based for basic combat. Bladesinger, too, gets Extra Attack, so full casters with Extra Attack are already a thing.
I kind of wish the class could craft a Crossbow of Loading or Repeating Crossbow, however. I suppose you could always take Crossbow Expert, however.
First thing I notice... Artificer's as far as I now are now the first class to be able to change out cantrips.
I don't think we've ever
not allowed players to swap out cantrips as long as it's within reason and you ask. I mean, they're described by the game as the most basic spells that you learn. They are, by it's own narrative, so simple that a beginner can memorize them. Even then, cantrips are relatively weak and not major game changers. Yeah, the game expects you to have one useful attack cantrip, but after that it's really all gravy. Granted, Artifacers get much better at swapping cantrips at level 10 than even we would allow, but it's still really not a particularly powerful ability.