I've contemplated the same thing using gas checks. Problem is, 32 cal gas checks are .323, not .312. That, I reason, could be a problem. I have contemplated getting a .312 cast bullet sizer and running them through. Thoughts on that?
Pill capsules not a bad maybe, but I know that these shot loads would see a lot of "travel time", hence the water solubility deal and durability is kind of significant.