A Mobile Manufacturing Plant is a type of machine.
While defenseless on its own, this large behemoth's biggest weapon is the ability to manufacture and launch powerful ballistic cruise missiles capable of destroying whole colonies in a single hit. Although they pose a serious threat, they cost a significant amount of resources to use.
They only appear when the Machines have calculated that its the best way to advanced in their plans and motives.
The missile itself however is slow and poses as a suitable target, meaning that a fast adversary can intercept and stop the projectile mid-flight. Such as in Go, Bernie, Go! when one was used to launch an attack on New Hammerston before it was stopped by Scrufflebeck.