Experimental Aviator

Flying
When Experimental Aviator enters the battlefield, create two 1/1 colorless Thopter artifact creature tokens with flying.

Sai, Master Thopterist

Whenever you cast an artifact spell, create a 1/1 colorless Thopter artifact creature token with flying.
{1}{U}, Sacrifice two artifacts: Draw a card.

Aspiring Aeronaut

Flying (This creature can't be blocked except by creatures with flying or reach.)
When Aspiring Aeronaut enters the battlefield, create a 1/1 colorless Thopter artifact creature token with flying.

Thopter Squadron

Flying
Thopter Squadron enters the battlefield with three +1/+1 counters on it.
{1}, Remove a +1/+1 counter from Thopter Squadron: Create a 1/1 colorless Thopter artifact creature token with flying. Activate only as a sorcery.
{1}, Sacrifice another Thopter: Put a +1/+1 counter on Thopter Squadron. Activate only as a sorcery.

Aviation Pioneer

When Aviation Pioneer enters the battlefield, create a 1/1 colorless Thopter artifact creature token with flying.