Yo Dawg, I herd u like Dodecahedron so I put a Dodecahedron in ur Dodecahedron so u can scramble while u solve!
This popular internet meme accurately describes this puzzle: it is a combination of two puzzles, a Megaminx inside a Master Pentultimate. Both puzzles turn at the same time so solving them requires inventing new strategies.
In effect, this puzzle has all the pieces that are present in the Megaminx, Pyraminx Crystal, Starminx and (Master) Pentultimate. The design of this puzzle was made by starting from a regular Master Pentultimate (using the shells mechanism, which already relies on an internal Megaminx to support the external pieces) and cutting holes in the faces. However, these holes cutting in to the mechanism would create a very much unstable puzzle so I've designed the parts with a wire-like structure that allows you to look inside the puzzle while enabling good rotation.
This puzzle was initially suggested by Carl Hoff, who coined the name Multidodecahedron.
The internal Megaminx has flat faces and is not spherical. However it is of course not a full Dodecahedron either, it is simply a sphere that has 12 caps cut off.
There is also a very subtle clicking mechanism (it is literally impossible to notice) that guarantees good alignment of the Pyraminx Crystal edges. I've designed the caps on the Megaminx faces to click in place so there's no need to glue them in place and the puzzle can (reasonably) easily be taken apart again.
As a consequence of the internal cutouts and wire parts, the internal pieces are not as visible as I would like but the puzzle is still fully playable. You just need reasonable good light and need to be looking somewhat straight at the faces. It was actually very difficult to capture this in the pictures (and video), but it's definitely not that bad.
The puzzle rotates exceedingly smooth and I could not have been happier with the result. It measures 35mm on an edge. The mechanism really didn't force the puzzle to be that large, but I wanted a reasonable area for the stickers. That said, it was a nightmare to sticker this puzzle and I had to use a toothpick to get the stickers under the Megaminx corners.