If you were going to make a case out of a monitor housing you would first have to strip all parts out of the inside. Generally only experienced techs trained for monitor service would see that done. Then the custom mounting of the board and power supply would be the next along with making precision openings in the housing for pci, usb, and other connections. Drive bays would see another set of openings made. Pc contests for custom mods would be a place to look where "anything goes" is the rule there.