Bart,
You'll have to fab it. How you do it will sort of depend on where you mount it (externally or internally accessable). I say that because I think an internal solution can be more flexable. For example, I wouldn't use a small section of piano hinge externally just because of cosmetics but I probably would on the inside.
Personally, I haven't thought this one through all of the way yet but I'm leaning towards externally accessible with either something like the oil door (hidden hinged on one side with a latch or camlocs on the other) or simply using camlocs or screws all the way around like an access cover. There's probably a million ways to skin this cat. YMMV.