This may be way out there - but if we change the phrasing, could we fit contraptions and riggers into this set?
Example -
Power Fusion Coils - 1
Artifact - Contraption
Assemble 2 - you may tap up to 2 untapped creatures you control. For each creature tapped this way add 1 mana of any color to your mana pool. Assemble a contraption only once per turn and only as a sorcery.
Rolodex - 2
Artifact - Contraption
Assemble 4 - you may tap up to 4 untapped creatures you control. For each creature tapped this way, put the top 2 cards of target players library into their graveyard. Assemble a contraption only once per turn and only as a sorcery.
Duplicator - 6
Artifact - Contraption
Assemble 1 - you may tap up to 1 untapped creature you control. If you do, put a token onto the battlefield copying that creature. Assemble a contraption only once per turn and only as a sorcery.
Little Rigger - 1R
Creature - Goblin Rigger
If you would assemble a contraption, ~ also assembles that contraption.
2/1
Fire-Fist Canonist 2RR
Creature - Goblin Rigger
Whenever you assemble a contraption, you may pay R. If you do, ~ deals 1 damage to target creature or player.
3/3
Skyline Rigger - 3U
Creature - Merfolk Rigger
Whenever you assemble a contraption, ~ gets +1/+1 and has flying until end of turn.
2/2
Scholar of Machina - 1U
Creature - Merfolk Rigger
Whenever you assemble a contraption, you may draw a card. If you do, discard a card.
1/2
Repair Call - 2/W 2/W
Sorcery
Put two 1/1 white artificer tokens onto the battlefield. If 4 was paid in this way, instead put four 1/1 white artificer tokens onto the battlefield.
Elton, Chief Operator - 2WW
Legendary Creature - Human Artificer
Whenever you would assemble a contraption, put a 1/1 white artificer token onto the battlefield tapped, assembling that contraption.
3/4
Iris, Assemblor Extraordinaire - 1UU
Legendary Creature - Human Artificer
Contraptions you control have Assemble X - where X is the number of creatures you control.
2/2
Thok Thok, Trash Picket - 2RR
Legendary Creature - Goblin Rigger
T: You may assemble a contraption from your graveyard. If you do, exile it at end of turn.
3/3
Technovirus - 2BB
Enchantment
Whenever a creature assembles a contraption, put a -1/-1 counter on that creature.
Plague of Parts - 3BB
Instant
Destroy all creatures assembling target contraption.
Clumsy Hands - 2G
Enchantment - Aura
Enchanted creature gets +2/+2. It can't assemble contraptions.
Slippery Fingers - 1G
Instant
Destroy target Contraption.