Riveting Rigger 
Artifact Creature — Cyborg Rigger
When this creature enters, you may sacrifice another artifact. If you do, put two +1/+1 counters on this creature and it assembles a Contraption. (Put the top card of your Contraption deck face up onto one of your sprockets.)
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyNOT LEGALvintageNOT LEGALcommanderNOT LEGAL