The original model by Noahghclark was too tall for me to fit into my tins, as the lip around the top was narrower than the body. I adjusted it to make it shorter and added slots for your thumb to slip in and grab cards easier. Also created a divider in case anyone wanted 3 separate compartments instead of 1 big one.

You'll need a hammer to get the 4th side into place. Put a sideA and 2 sideBs into place inside the tin, and then position the last sideA into the notch of the sideBs and hammer it in.