This seems like a good solution https://www.amazon.com/Rosewill-Universal-Cantilever-Cabinet-RSA-1USHF01/dp/B06XDV81WN
They are mounted crazy, somebody drilled holes in them and mounted them all together with metal strips. Now I need to replace some, but I can't get to them one at a time.
The shelf is a few inches deeper than the switch. Here’s the shelf I bought
Rosewill 1U 10" deep https://www.amazon.com/dp/B06XDV81WN/ref=cm_sw_em_r_mt_dp_U_b2cDCbED276K8