I have done custom noctua fan adapters for other GPUs lol. But that requires the person to have a good understanding of reading vernier calipers. The result was one hole being slightly offset.This kind of stuff is why I frequent the forum.
If i had more GPUs (even broken ones) i could most likely design 4 liter cases.
I can currently design a 3.5 liter case but only the NH-L9A/I can be used and Custom GPU adapters because the OEM manufacturer specifications for the mounting brackets waste too much space (which is the reason why i had to make a custom adapters for my Zotac 2070 and 3070)