We use these for all sorts of things, too. :) Water and hay tubs for calves in their night pen, seats to sit on, a platform for filling the chicken feeder, a step stool for a couple of heavy roosters who can't make it up to the top of the stall gate (and then into the rafters) in one flap, and I have a bunch of the heavy black ones out in my garden, which is mostly containers now. We drill holes in the garden tubs for drainage. My old knees won't let me get down low to the ground anymore, but I can sit on a folding chair in front of those tubs and be right at the perfect height for weeding.
The best part is, the calves (and sometimes the grown cows, LOL!) can play with these and toss them around to their heart's content with hardly any damage, but if one DOES break, there are always more. So far, I haven't had any broken by the cows. Some of our orange ones (similar to the blue one in the first post) have cracked just from hot/cold weather exposure, but the black ones seem much sturdier, and we've been using them for years and years now.