This is a twist-lock dust cap for a generator inlet box with a CS6375 (SS2-50P) power inlet connector.
I have the GE T050N inlet box which, according to Amazon reviews, is prone to wasp nests and mud dauber wasps. I designed it by measuring the cord connector, so I can't say that it meets the official connector dimensions, but the end result is a smooth fit and twist-locks into place just like the generator cord.
Must be printed with supports -- mainly for the handle.
I don't think the plastic type matters for this object. I printed mine in PLA, because my cap will not be exposed to sunlight. If your conditions are different, you might consider a different type -- like ASA.
generator_inlet_cap_for_CS6375.stl | 301.8KB |