The poster over the foam is probably the neatest part to me. Solves the hole size issue and looks better than raw foam or even the colored plastic that Capital uses.
I think you could sell enough of them through this forum to pay for a coin or two to fill some of those holes.
This is an improvement over Capital Plastics holders with some light tweaking.
If you made both top and bottom clear sheets thicker you could probably minimize some of the tooling for all the fasteners. Probably cheaper that way in the end when labor isn't free.
You would also only need to stock the one part thickness for top / bottom sheet then too.
Last concern I would see would be the paper and ink for the poster. You wouldn't want any interactions between them and the coins over time.