This is for a laser cutter - I cut it out of 3/16" foamcore, but you can use whatever you like and alter to your needs. I've included the .AI file to make it simpler. It makes 16 slots, but it's easy to edit and make more or less. I also included a JPRG of the labels I applied for sorting Pokemon cards. The black lines cut through and the blue cut at least through the first layer of cardboard, so that the foamcore can be folded back. I used hot glue to fasten the pieces together.