Josh,

I didn't find any neat colored sheets at the usual places and never fully explored the brick-n-morter world of plastics. But, there are lots of websites that carry this stuff. Some are: http://www.ridoutplastics.com, http://www.usplastic.com, and http://www.modernplastics.com. There's usually much more of a choice with acrylic sheet, but you need to be careful not to let it get too warm and melt. One thing I've done is to use a finer tooth on the jigsaw. Sometimes the stuff will just chip and act up. There are special bits and blades you can buy for working with plastics too. Some of the knife supply houses carry beautiful marbelized acrylic blanks, but it's usually a little too small (and often too thick) for us razor dudes.

Good luck and have fun,
Steve