So I was curious what the thickness was for each separate foam? Also I'm not sure if I heard correct. But is the yellow foam evazote? And the blue and black one you said were puzzle foam mats right? The ones people use for baby flooring?
Good ideas there, definitely worth including in my next batch. Hockey tape is a godsend - so much better than using duct tape for something like this. Very clean look, saves on weight, durable as heck. Side note about the "defacing money" thing - it's not illegal. It is illegal to alter currncy in order to pass it off as a different denomination (counterfeting), but it's totally cool to drill holes in coins to use them as custom washers.
Gabriel: Don't thank him for all the other thoughts or effort or anything as you put in your two cents (forgive me I mean pence or krones or something).