noel wrote:
Hi,
I want to build a couple of pc cases and a few trays. The
front/back panels I will probably have done on a cnc machine. And the
top/side cover I'll probably have done by a shop. What I will want to
build is the base/internal box and support structures for the mother
board, drives, power supply, and such.

Have you made sure that you can't in fact obtain what you want?
For example, go to http://www.ebuyer.com/ and peruse the case list.