This is a cap for 50x25x1.6 RHS, which I used as the feet for my work bench. If you have solidworks, you can download the source file and adjust the thickness of the base (currently 2mm) as required to assist in leveling your bench. The concrete under my house in uneven, so I was able to customise the height of each cap to get the bench nice and sturdy.
I've blogged about this work bench here:
https://teslaandi.wordpress.com/2018/09/16/scrounged-work-benches/
bench_RHS_cap.SLDPRT | 238.5KB | |
bench_RHS_cap.STL | 29.6KB |