The Reuleaux tetrahedron is not of constant width. But the Meissner body should work.

Are you asking about the packing-covering problem (see e.g. arXiv:math/0412320)?

PS, when you put "one more layer between my work and would-be copy-and-pasters", this is what happens: twitter.com/KyleCranmer/status/465935221796634624/photo/1

Regarding concerns about posting tex sources: arxiv.org/help/faq/whytex. The discussion there applies to this case, except that when you post to your own homepage, it doesn't help much as a timestamped archive for priority claims. A website of the type you seek would help in that regard.

That sounds like a good idea, but I have to wonder why your question is restricted to beamer presentations? Just like the arXiv is not restricted to LaTeX papers, why should a site like the one you mention not accept keynotes and power points? That said, I also post my slides on my website, with source code. One of the great things about arXiv is that whenever a paper is written in LaTeX, it is always provided with the source code. I saw you do not post your beamer source code, and I was hoping you would consider changing that.

@YemonChoi Given an arbitrary underground map as an input Mornington Crescent is probably also undecidable. The proof is trivial if going around the circle line more than once is not allowed. That should not arise in normal play, but I'm not sure how to prove it.

Unless you are using "simple" in any technical sense, then no, part of the gag is definitely that the program is inscrutable.