The mecha spawning pool is a structure available to Egon Stetmann in Co-op Missions. It functions much the same as a normal spawning pool, with the added bonus of allowing Stetmann to respawn defeated zerglings from scrap parts. At level 13, while the talent says it doubles mecha zergling and mecha baneling remnants, it instead lowers the amount of remnant required at the spawning pool from 4 to 2.
Mecha spawning pools do not require creep or egonergy fields to be constructed.
Mecha spawning pools will burn down when put below 1/4th health like terran structures, but can be repaired by mecha drones.