My mind is BEYOND blown. Those are AMAZING!
EDIT: I just went and looked up Micromen figures online... they seem to be very hard to track down. Where do you buy yours from? I would buy one and then make casts of the various parts, myself.
It'd be incredibly difficult to cast the parts... otherwise I think someone would be doing that. There are TONS of articulation points, and they would be very difficult to replicate with a built at home molding/casting system.
I have bought micromen on e-bay before. There are versions that have mounting points for accessories, you can get them and then just dremel the parts all down smooth... which is what Stitchfett does.
but your right, they are rather hard to track down, and when you do they are usually expensive.