This is a new wallet back embossing plate cut into delrin. I took a fishscale (or dragonscale if you prefer) checkering pattern and transfered it over. I've added a closeup of the scales. I'm thinking of redoing this and adding just a hint of a border to better protect thos outside scales, but otherwise pretty pleased with it. this was cut with a 1/16th bullnose.
Yes, it's white delrin 1/2" thick. The leather should be wet. That softens the cells so it can stretch and take the impression and once it dries it will hold the shape. this was pressed using my 1 ton arbor press. I back it with a thick piece of leather or rubber so that it presses the leather up into the recesses. If that's not enough, I also have a 12 ton bottle jack press that will take care of business. but 1 ton is usually enough. Delrin is my material of choice but most anything can be used. It only has to be harder than leather to work. Cheers!