Hey Keiji, good to have you active here again, it's been a while!
Sad to say, I have hardly been keeping up with discoveries lately. Mostly just doing what I can to keep my website updating in a semi-regular fashion (has been better since last year when I made a large enough buffer of Catalan solid entries that I could continue posting monthly in spite of often having no time at all to do anything 4D or 3D related). I'm dreading the day my buffer runs out, then I might have to go on hiatus again.
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Anyway, since I'm at it, might as well include the latest entry on my website, that I haven't gotten around to posting here until now:
This is the so-called "bidecachoron", the dual of the bitruncated 5-cell. (Not perfectly happy with the name, I got the name from the Polytope Wiki, apparently coined by Bowers. But for lack of a better name, it will have to suffice for now.) Interestingly enough, the projection envelope is a cube, and the layout of cells in it embodies the two ways one could inscribe a tetrahedron in a cube. I'm sure there's a rational reason behind it all, of course, but it's just an interesting coincidence that struck me when I was doing these renders.