Retrofitter Foundry

{3}: Untap Retrofitter Foundry.
{2}, {t}: Create a 1/1 colorless Servo artifact
creature token.
{1}, {t}, Sacrifice a Servo: Create a 1/1 colorless
Thopter artifact creature token with flying.
{t}, Sacrifice a Thopter: Create a 4/4 colorless Construct artifact creature token.