Sorry for the terrible-quality picture, I'll try to get better ones up tomorrow. Basically, it introduces the 'hidden centers' from PM6262's mixup cube as external pieces.
I've drawn a mixup- dodecahedron and a mixup- octahedron, both of which cannot actually be made from a normal mixup cube. If someone prototypes one of these it will open up a whole new realm of mixup cube shape mods.

Anyone interested in giving it a shot?

thanks for watching

sj

With your permission, I would like to put designs for these on shapeways. I already have the design so it would be very easy and not need to be prototyped.

Permission gladly granted! I'd love to see these puzzles on Shapeways.
(I'm actually really interested to see what the Dodecahedron will behave, I wasn't able to get the correct angles on my sketch)

First one done!