1/8" solid Walnut from http://www.gvwp.net/
Entire joint length is about 1" (1.02 or something). The fingers are about 0.035" wide. I think I could probably take them down to about 0.02". I tried at closer to 0.015, and it scorched to death.
Manually rounded corners with sandpaper, sanded to 600 grit, then hit with a coat of Feed-n-wax. I like the look, I think I will incorporate it in my next project.
Scorched to death: