Followup if anyone finds this - not the greatest. Discs have a tendency to fall through if they rotate even a little on the shelf. Considering adding some pool noodles or conduit or something to maybe the bars grippier and effectively closer together.

Expensive at $23. You can see which holes I used and skipped. Works pretty well.

Whitmor Stacking Shoe Rack, 9-Pair

https://www.amazon.com/dp/B002PX8EIK/ref=cm_sw_em_r_mt_dp_R3KWHA90NNYE9BBS1P6V?_encoding=UTF8&psc=1