I wanted to do a really simple design based on those old Wile E. Coyote cartoons where he paints a tunnel on the wall and a real train comes out.rnrnI thought it would work best on white or light gray, but please let me know what you think. Any comments would be greatly appreciated!

Great idea, I'd say it would look more cartoon-ish if you added some colors.

Feel free to comment on my design:
http://www.threadless.com/critique/78977/Icebreaker