Sega Mega Drive/Genesis case for Sega and EA-style game cartridges

I've been collecting some old Sega Mega Drive games, but most of them don't come with cases. There are some mass-produced options for replacement cases, but I don't live in an area where it's practical to get them delivered (they would end up being quite expensive with shipping)

So I've designed a simple 2-part plastic box to securely hold the cartridge in place, which can be covered with a printed paper sleeve for shelf-display.

Cartridges licensed/manufactured by Sega are a certain shape