Not sure if this is new to others or not, but I tried a new technique on hollowing today and it worked very well. I had picked up a few of the CORPS! mini-jets on clearance and didn't like that goofy face the pilot had, but liked the helmet. The head was of that softer plastic that bores out good with a dremel. The problem I always had was finding a good way to hold the head still while I dremeled it out.
I had a small stack of pop bottle caps sitting on the workbench that I use for mixing paint, epoxy, etc. I decided to fill it with my kids play-doh and jam the head down in it. The idea was that the dough would keed the head protected and still while I could keep a good grip on the cap. Unfortunately the play-doh was too soft and the head spun out, but super sculpy worked perfectly. You may have to pick off a few chunks of super sculpy when you are done, but the set up allows easy and safe drilling. It also was easier shaving the edges off with an exacto without getting your fingers in the way. The ridges on the cap allow for a good grip too. Thought this might come in handy for someone.