I need to fit a fully-functioning mobo with an LGA1151 cpu socket and a PCI-E x16 slot for my gpu and at least 2 RAM slots in a 11 x 5.5 x 7 case. It also has to have a maximum RAM capacity of at least 32GB. No need for fancy stuff like LED controllers or anything though. Just the bare functional basics, because it will be in a very closed off case, so it doesn't need to look nice at all. Does anyone know of a 1: Very small but full-featured motherboard, or 2: a company that would be willing to manufacture 1-2 motherboards of a very small size for a couple hundred dollars. Any other options would also help, but those are the main 2 things I'd be looking for. My budget per board is around $250, give or take a bit.
EDIT: I've read around a bit, and I've figured out that it will probably be way too much money to make a mobo, but what about modding an already made one?