This is a cartridge shell for the Neo Pocket Flash Masta which is a cartridge for the Neo Geo Pocket Color video game console. It was made by Eric at https://www.badaxe.co/
If it looks way too small, you may need to scale the STL by 25.4 to convert from inches to mm. It seems that lions3 has posted a metric version here (https://www.thingiverse.com/thing:2374831).
You may need to scale by 25.4 to convert from inches to mm.