Case Creation

Thinking of making another computer. But this time, I was thinking about making the case. So what precautions do I need to take? What material is best? Is plexiglass good for a window? I'm also working on a awesome fan design whic, if it works, should be the fastest and best of it's kind. Also, anybody who helps with this can have a free one. They not hard to make.

I made a case out of wood once. Its basically a frame with mounting holes, and was incredibly sketchy. I had some old parts (a Pentium 3 for example) so I took them down to my basement workshop and started cutting wood.