The Autons in the mod do not do much. In fact, it makes little sense that they even exist, given that the Nestene Consciousness is not present to give them life.

I propose to add the Consciousness, as a boss mob. This boss would spawn in its own plastic-themed structure. It would be able to spawn Autons to defend itself. As for location, I believe this structure should spawn on Varos, a planet known (in the mod, at least) for the plastic growing in its trees and underground.

Nice idea, I would have just thought of a shop in the overworld, but it seems they don't try to add overworld structures.

also in the overworld, plastic factories.