From page 66 of the magical new Tim Holtz book "Compendium of Curiosities Volume 2".
Custom Foam Stamps
Also, to show my process, I thought I'd share the two I did before this that I didn't care for. It's all part of the journey!
Wish me luck in the challenge at Studio L3. Enter your own creation for a chance to win a prize from shopping site extraordinaire Simon Says Stamp.