Revised Artificer

I really like the direction you went here with the Artificer and I think you're onto something. Especially the Clockwork Familiar and Clockwork Guardian options. My only concern is that the overall damage of all 3 subclasses fall short on damage at higher levels due to the separation of the Clockwork Guardian into it's own subclass. Here are some things that stood out right away.

* The Alchemist loses a single target attack option for higher damage. Leaving them at a significant disadvantage in combat vs tougher solo enemies. On top of that, all their damage effects are AOE, meaning they will likely hit themselves at close range. Bring back a single target acid attack for 9d6 at highest level (27 average damage), and make the Acid and Wand/Gun attack an actual spell attack roll (not a saving throw), so the player has an alternative attack option vs creatures with very high saving throws. Plus it's not very fun watching the DM roll the dice to for you to hit all the time.
* By the D&D law...See more of averages, at 17th level she will be doing 5d6 or 18 points of damage as a 10 foot cube (4 battle squares).
* Most classes in 5th edition are designed to do nearly double that damage vs a single target at 17th level. Or supplement their damage with higher AOE level spells and magic weapons.
* AOE wise, it also falls a little short at 18 pts of average damage, because it's only a 10 foot cube. High level enemies will be in groups doing 3 attacks per round, throwing Chain Lightning, higher level Fireballs, or causing massive AOE damage at 17th level. But the Artificer's contribution will be limited to an average of 18 pts of damage, to 4 creatures standing near each other, if they're so lucky.
* So I think the original class design included the Construct creature as supplemental damage for the original two subclasses.

As for the Wand Expert and Clockwork Engineer, the single target damage falls short for the former and the AOE damage falls really short for the latter. Consider looking at the power and damage output of the Revised Ranger, including all their class damage abilities, AOE options, two attacks and Hunter's Mark. Or the Arcane Trickster who can use Green Flame Blade along with their Sneak Attack for insane amounts of damage consistently. Or the Paladin who uses Smites. Or the Fighter who eventually gets 4 attacks per turn (possibly 5), plus ability score and weapon bonuses per swing, and then will be able to use Action Surge to turn that into 8 or 9 attacks for two separate turns at 17th. Or the Barbarian who gets 2-3 attacks per turn with devastating critical damage occasionally. Or the Valor Bard who can do Synaptic Snap AOE damage in a 30 foot radius, then get a bonus action attack, and a Haste attack in a single round.

So I think you're onto something really great. But may have dissected the original design a little too much. If you keep them as 3 separate subclasses, consider giving them a single target option for higher damage as before, more status effects for their AOE attacks so players use more than 1 or 2 (cantrip secondary effects are a good place for ideas), and maybe even throw in some kind of home made tinker guns and repeating crossbows for the Clockwork Engineer to make him feel a bit more powerful.