Looks to me like someone used lamp pipe and lamp pipe caps;
https://www.amazon.com/Westinghouse...pcontext&ref_=fplfs&psc=1&smid=A3FXLCMUZ5EJPB
100's of variations out there.
https://www.amazon.com/Westinghouse...pcontext&ref_=fplfs&psc=1&smid=A3FXLCMUZ5EJPB
100's of variations out there.