My nails (and hands) have disintegrated altogether under pressure of sewing/cooking/etc (I think it was turning through that bloody dragon kit that finished them off).
Rice Krispie treats - I searched a few websites to find out what you do differently if you are making it for structural purposes rather than just to eat, as I was fairly convinced that what I make for eating would be way too soft. Two answers came back:
- make it as per the "recipe on the box" (which I am assuming is the same as the Mary Berry recipe, since I haven't bought real, branded Rice Krispies ever that I can recall) but without the butter
- buy the ready made ones (the Kellogs Rice Krispie Squares, which are annoyingly not even square)
(1) makes sense to me, but could be tricky, as you would be melting together toffees and marshmallows with nothing to dissolve them in, IYSWIM. I guess you could do it in a double boiler and it should be fine.
However, since I was only making a dragon head I went for (2) 
The next challenge is how to get it flat enough to ice. Again, 2 options - either you blitz the rice krispies a bit in the food processor before mixing them in, which gives you a denser, but smoother end result, or you coat the finished item in white chocolate before icing - which is what I went for, and it seemed to work well - Dragon's head was still crunchy when we murdered him.