I have used milliput (see http://www.milliput.com
) a little bit, but there are also still a few questions I would like answered from anyone who has more experience with it than I have. First a quick description of the stuff.
It is two-component epoxy putty. It comes in several varieties, but I have only used the standard greenish one (it also comes in white, or terra cotta)
A box has two bars (green and grey) of putty. After kneading together equal amounts of each, the stuff begins to harden. This process takes a couple of hours at room temperature. After 4 hours it can only just be scratched with a fingernail, and a few more hours and it is rock solid. You can put a mixed batch in the freezer to suspend the hardening process.
Once hardened, it can be filed and sanded down to whatever shape you want. The material has no elasticity to it, so it may not be suitable for the mechanical parts of a twisty puzzle, except for prototyping, or unless there are some springs in it as well. I don't know how quickly it will wear. On the other hand, it is certainly very good for building different exterior shapes on top of existing puzzles.
You could certainly use it to build prototype puzzle pieces, from which you can then make moulds. On the milliput website there are actually reports of people making the moulds from milliput, in order to make copies again in milliput.
Anyway, questions I would like answered are:
How suitable is it for a puzzle's internal mechanism? Has anyone tried this?
If it is suitable, how quickly does it wear down, and how much stress can it take?