I am new to pepping also. I found a great tutorial on youtube for pepakura designer 3. It showed how to put in your body measurements then drag each piece of armor (file) into a box on the left and it would do the calculations for you. Sorry for the vagueness but it might get you in the right...
I know that if you add this stuff called microballoons to your resin, be it epoxy or polyester resin that it sands great. I would compare it to joint compound/spackle for drywall. Sorry this belongs with post #61, hit reply instead of with quote.