This is a helpful guide. He had square buckets, mine are rectangular. And his square lids are not hinged (so probably more leakproof). Also, his buckets were easy to debrand by taking off the plastic sheet of labeling. Mine had "TIDY CAT" molded and painted everywhere, so I sanded it down and spray painted it with grey primer, then applied reflective stickers ("3M Conspicuity" ordered from eBay, then cut up with an Xacto knife)

Apparently it is likely you can find suitable lidded buckets at home despot or lowes or something.