Mouser is a distributor for Hammond enclosures. I've bought several of them: plastic and steel ones. They have an enormous range that will fit almost anything.
I also print a lot of enclosures on my 3D printer, or use some of the Hammond parts with my own printed parts.
Another good source is the kind of cases that have a transparent lid. They are often waterproof, with a rubber gasket. I end up drilling holes in them for my buttons and wires so they aren't waterproof but the LCD is bolted to the inside of the transparent lid. I buy them from Jaycar, Mouser, even Radio Shack sometimes.