Throne of Geth + Dross Scorpion + Animation Module + Workhorse

Throne of Geth

Dross Scorpion

Animation Module

Workhorse

How it works

1. Activate Thrnoe of Geth by tapping it and sacrificing another artifact creature.
2. The artifact creature dies, triggering Dross Scorpion, untapping Throne of Geth.
3. Resolve the Throne of Geth ability, putting a +1/+1 counter on Workhorse.
4. Animation Module triggers, holding priority, activate Workhorse by removing a +1/+1 counter from it, adding C.
5. Resolve the Animation Module trigger, causing you to pay 1 to create a 1/1 Servo artifact creature token.
6. Repeat.