The Artificer was recently re-released on Unearthed Arcana, and I had a few build ideas, so I decided to post them here. NOTE: If an Artificer class forum is made, this is to be moved to that forum. The builds are as follows:

Armorficer:
The armo(u)rficer is an artificer who maxes out their armo(u)r and other defensive abilities.

• Pick High Elf as a race-- DEX and INT increases are great, especially since you will need maximum DEX for AC.
• Buy your equipment and get studded leather armo(u)r and a shield (and weapons, an equipment pack, tools, etc) and attempt to max out Dexterity-- even though Intelligence is supposed to be your main stat, if you can get your DEX or INT to 20, pump DEX first priority.
• I'm not going to write in spells, but spells that improve your AC (e.g. shield, shield of faith), spells that give you hit points (e.g. false life, resistance), or spells to keep enemies away from you (e.g. ray of frost, grease). Mending is also useful as to heal your turret or homunculus.
• At 2nd level, learn the Resistant Armor infusion along with 2 others. Try to use that infusion on your armor as soon as possible-- Dex 20, studded leather, a shield, Enhanced Defense, and Resistant Armor get you a 20 in AC (21 at 12th level).
• At 3rd level, choose either subclass. Although the Alchemist is mainly support, the spells involving healing or warding bad effects, salves created by your homunculus and greater/lesser restoration can be used on yourself, the bonus to healing spells can include self-healing spells, and you gain resistance to acid and poison damage and immunity to being poisoned. Make your homunculus use the Resilience salve on you over and over again (up to 3 times) during combat. The Artillerist is somewhat more straightforwardly defensive-- you get great defense spells like shield, thunderwave, wind wall, wall of fire, and wall of force, the ability to make a Defender turret (heal yourself!), a wand which you can put a defensive cantrip in, and a wall of force to protect you and your party. You should infuse your wand with resistance or ray of frost.
• At 4th level, take the Boots of the Winding Path infusion-- it has something to do with armor, and teleportation can keep you out of trouble with enemies.
• At 8th level, swap out whatever infusion you learnt at 7th level for the Resistant Armor infusion. This makes your armor grant you resistance to a damage type (try to pick a damage type which is common in your campaign, for example, if the Big Bad is a red dragon, choose fire.)
• At 18th level, store any 1st or 2nd level one-action defensive spell in your shield-- this allows you to activate that spell at all times, given that you'll always be wielding your shield.

Netificer: I created this pretty simple Artificer build around the idea of making nets not as broken, though I'm not sure if it totally works.

• Take basically any race, especially one that increases INT and DEX.
• Start with a level of Fighter so that you can get the Light, Dark, Underdark! Close Quarters Shooter fighting style, because nets are perpetually used with disadvantage otherwise-- their normal range is 5, which gives you disadvantage, and using the long range gives you disadvantage as well, but Close Quarters Shooter allows you to use a range of 5 feet without disadvantage. Take a net as your starting weapon.
• Then take Artificer levels, and at 2nd level, you should take the Returning Weapon infusion as one of your infusions, and use it on your net. This is the part that I think might be broken-- the net might not work because if it just teleports back into your hand, the creature is no longer restrained. I've asked for clarification on this on one of the other threads, so I'll either delete this build or clarify that, depending on the answer. I don't have any other needed things for this build, but Enhanced Weapon and Radiant Weapon would be good for +1 to attack rolls, and spells that enhance your net are nice. This build is actually useless, given that the net will just immediately return to your hand-- Wizards should consider changing it so that, as a bonus action, you can return the weapon to your hand, or a Net of Returning would drag back the creature in it.

Weaponsmith: This artificer build empowers their weapons as much as possible.

• Take a race that gives you INT and DEX or STR, and start with some sort of thrown melee weapon in your equipment as your main weapon.
• Spell-wise, you should be taking arcane weapon, magic weapon, elemental weapon, heat metal (to make your weapon deal fire damage), and other spells along those lines.
• At 2nd level, take the Enhanced Weapon and Returning Weapon infusions, and give them to your main weapon.
• At 3rd level, choose the Artillerist subclass-- it grants you a turret and a wand, which you can make in the shape of a weapon and store a damage-dealing cantrip in it.
• At 8th level, replace one of your infusions other than Enhanced/Returning Weapon with Radiant Weapon, and give it to your main weapon.
• Finally, at 18th level, store heat metal in your main weapon. You can now heat your weapon at will for a while. I'm assuming that you only heat the tip of your weapon as opposed to heating the whole thing and hurting yourself, but correct me if I'm wrong.

Supportificer: This artificer focuses on supporting their party.

• Choose any race, preferably one that improves INT.
• Spell-wise, take spells that provide buffs (haste, darkvision, spider climb, guidance, etc.), healing (cure wounds, spare the dying, lesser/greater restoration, etc.) and protection (protection from poison, shield of faith, sanctuary, etc.) to your party.
• For infusions, Boots of the Winding Path, Enhanced Weapon, Enhanced Defense, Radiant Weapon, Resistant Armor, and Returning Weapon are all viable because you can give those enhanced pieces of equipment to the party. You could also consider brewing 1 or 2 healing potions if you're proficient with alchemist's supplies or the herbalism kit, and creating a Many-Handed Pouch-- this way, you can hand out pouches to the whole party and they can all access the potions, rather than having to spend the time and money to make 10 healing potions.
• At 3rd level, for your subclass, although Alchemist seems like the obvious choice, Artillerist is also viable. As an Alchemist, you gain a homunculus which can hand out buffs+healing, and later gain enhanced healing and the ability to cast lesser/greater restoration at will. As an Artillerist, you should choose the Defender turret, which will allow your teammates within 10 feet of it to regain hit points. You should store either spare the dying, resistance, or guidance in your wand.
• In your Spell-Storing Item, put any one-action support level 1 or 2 spell.

Those are all of the interesting artificer builds I can think of so far. If you have suggestions or ideas for a build, write them here!

Sorry to disappoint, but you can only store artificer spells in items if there casting time is exactly 1 action - so Shield and Shield of Faith are prohibited by their respective casting times of 1 reaction and 1 bonus action. Also you still have to concentrate for spells cast from items, so I really hope that Artificer has better things to concentrate on at 18th level than Shield of Faith! ^_^

Same goes for Arcane Weapon (bonus action) - to be honest I think it's a bit of a dud full-stop from level 5, with no scaling and the concentration requirement.

Can't say I agree about putting Resistance in a wand; besides the concentration aspect (too many tiny concentration spells in this spell list), literally the only benefit of wand vs memorizing the cantrip is to get the bonus on damage rolls.

In practice I guess an artificer only ever needs to remember their one favorite concentration weapon/defense buff, Heat Metal & eventually Haste too - the rest can go on attacks and utility.

Quote from Vorsa >>

Sorry to disappoint, but you can only store artificer spells in items if there casting time is exactly 1 action - so Shield and Shield of Faith are prohibited by their respective casting times of 1 reaction and 1 bonus action. Also you still have to concentrate for spells cast from items, so I really hope that Artificer has better things to concentrate on at 18th level than Shield of Faith! ^_^

Same goes for Arcane Weapon (bonus action) - to be honest I think it's a bit of a dud full-stop from level 5, with no scaling and the concentration requirement.

Can't say I agree about putting Resistance in a wand; besides the concentration aspect (too many tiny concentration spells in this spell list), literally the only benefit of wand vs memorizing the cantrip is to get the bonus on damage rolls.

In practice I guess an artificer only ever needs to remember their one favorite concentration weapon/defense buff, Heat Metal & eventually Haste too - the rest can go on attacks and utility.

 I've edited based on your recommendations.

so uh arso artificer attach eldritch flamethrowers and control flames there