Yea, vacuum forming is the way to go.
If you glue and or dremel PCB, it will turn out terrible no matter what tools you use. It will also be hard to work with as it will crack, split and chip because it is brittle.
You can easily build a vacuum former that will do the job (as I was going to do) with basic wood working skills. See Marshallh's site (http://retroactive.be/l64/
) and you will get a basic idea of how to do it.
If not, I accept Commissions. (VIA my site).
So build a case out of wood yourself (IE: Mould) and then send it over to be professionally vacuum formed using my schools $8300 one!!!