Foam might work well, Shadow Fox cases clips actually hold all the cards, I think.
Bt e-Reader accessories, do you mean the e-Reader itself? I have a cover almost done, minus the spine, same with a Green GB Camera, I can modify that to blue.
I can make a GB and GBA Triple spine easily.
I have GBC and GBA double already made for Wario Ware, Pokemon Pinball, and Perfect Dark.
I have a modded case order for Wiggy for a long time, I think they broke and he needs to make more.