Q: HD black tubs have a molded-in keyhole shape on rim??

[snakesRkewl]

Thanks Jerry!
if you have a chance at some point, could you post a pic of one of your tubs with the bolt and washer?

All our rats are at my partners these days.
All you need is a bolt that will fit into the hole and long enough to put a washer and nut on it.
It helps if the washer is a bit over sized so it covers the entire hole so they can't chew on it.