Interesting you say that, some Apple iii's never upgraded to the 12v Card some still use 5v even though a 12v should work just fine as it was an upgrade. My Apple III is the Plus variant and I'm 90% certain I'll find the 12v card inside. I would consider it I think one of the Apple ii fan cards...
This is neat, very professional looking. Update on the lid here's a photo I have to swap the Plus badges to this standard Apple III case so if anyone needs badges let me know! I'll even throw in a broken case lid.