I love what you do and have for well over a decade, but much of your case design is now outside the realm of normal hobbyists who lack 3D Printers, advanced software, CNC Machines, or laser cutting devices. So why not give us a more old school and amateur-friendly build that we can do at home with more basic tools? A VHS Tape has an opening up top that can close itself when not in use for battery and cartridge access, it has good size, it has grip on the back, the windows for the tape can be removed and replaced with covers housing inputs and a speaker, and it is suitably retro. There's even a nice place in the middle for a screen. A Raspberry Pi, an NES on a chip, or some other compact solution would be great in such a case! Show us that we don't need fancy equipment to make something we can be proud of and enjoy.
If you do an NES on a chip, you can perhaps avoid the issue with the 72-pin connector by hard-wiring in a Game Genie. I would like to see a 4:3 aspect screen if you went with a dedicated old portable instead of a Pi, but it's understandable if those aren't available.