Snub Disphenoid, the convex deltahedron with twelve faces
Pieces required: 18 ZipStix and 8 zipties
1. Build a pentagonal bipyramid, making sure to keep all of the junctions loose.
2. Note that there are two corners (the “top” and “bottom”) at which five ZipStix meet, and five corners (the “sides”) at which four ZipStix meet.
3. Release the ziptie at one of the side corners of the structure. Unlink one ZipStik that comes from the top corner, and replace it with a fresh, unused ZipStik. Re-link the side corner.
4. Your structure should now have two fringe ZipStix: the one from the top corner that you released, and the new ZipStik that you added. Link the free ends of these two, together with the remaining two unused ZipStix.
5. Take the free end of one of the ZipStix added in step 4, and identify the side corner adjacent to the one you released and re-linked in step 3 which is nearest to that free end. Open up that corner and add the free end to it, and link it back up.
6. Repeat step 5 with the remainig free end of a ZipStik and and the other side corner adjacent to the one you released and re-linked in step 3.
7. Look over the structure as a whole and if everything looks OK, tighten up all of the junctions.