by grafalex

Astrominx is basically a shapemod for Starminx II puzzle. It is made in a form of icosahedron where icosahedron corners match dodecahedron centers, and icosahedron centers match dodecahedron corners.

Some of the Starmins II algorithms work well for Astrominx as well. But need to keep in mind that Astrominx corners orientation now maters (unlike starminx centers where orientation does not matter)

Number of parts to print:

• 1x Core

• 12x Inner (Megaminx) Center

• 30x Inner (Megaminx) Edge

• 20x Inner (Megaminx) Corner

• 30x Outer (pyraminx crystal) Edge

• 60x Trianges

• 12x Outer Corners

You will also need 12x 0.5x4x10 springs (can be bought on aliexpress) and 12x of M3x20 screws with a small head.

As for printing. My favorite technique is to split each pieces into 2 halves, print them separately and glue haves together. This allows printing without supports. Such split pieces come with 'Split' infix in the file name. If you still prefer normal printing - I added 'As Is' parts as well.

As for other print settings:

• 0.3mm or 0.4mm nozzle

• 0.1mm layer (0.2mm is also ok, but will probably require more sanding)

• 2-3 perimeters, 20% infill

• cooling as needed

• no supports for 'split' version

I recommend ABS plastic as it is easy to sand. PLA and PETG will also work well, but they are way more harder to sand. ABS can be glued with acethone, PLA/PETG work well with dychlorethane. My personal opinion is that black plastic would look much better than white/natural I used.

I experienced some corner wrapping issues while printing (until I found a right amount of cooling). That is why I added some Mickey Mouse ears. Just cut them with a knife before gluing.

Core piece has a few througholes. They are needed for precise positioning of the halves, as well as to improve inter-layer adhesion (core part and megaminx centers should accept pretty big forces). Just glue pieces of filament there.

Printed/glued pieces will probably require some sanding to remove surface unevenness and glue the seam. After that outer pieces can be painted with a spray paint. Final thing to do is cut stickers.

Turning quality demonstration: https://youtu.be/C7Dq38hnfEg
On the video the puzzle is pretty catchy. Later I tighten screws and it became a little stiff, but less catchy. I solved the puzzle couple times, nothing pops up so far.

Onshape source (see Astrominx tabs): https://cad.onshape.com/documents/4511491b885827802c8245d6/v/9e3d2e06edc050b3a977d3ab/e/1e40190713bae05b5c61a167

Bug thanks to Sam who shared his Pentultimate sources in Onshape. I could learn how that puzzle was built, and also understood how to design other similar puzzles (Starminx II is technically a subset of Pentultimate's mechanism). I would also like to thank kskmaru for the idea of such a Starminx shape mod.