Instead of re-texturing the solid cubes with just new textures, why not go with a dynamic theme of rendering something from an input/output of the machine itself? So for example a generic solid cube model with an inset box in the middle of the front side that renders say for example in the Chopper, the Axe it's currently using, or the Crusher renders the ore it's currently processing.

Updated: Like this?

Maybe even add a simple RED[off]/GREEN[on] light indicator to show it's currently working or receiving power.

Closing this for now, going to pair with a asset creator for new design