Sam’s Club bakeries give away their 3 and 5 gallon buckets that icing comes in. Add a mylar bag and an O2 absorber and you’re in business! ;-)
I read somewhere about being careful not to use buckets that had any kinds of fats or shortenings previously.
I wish I could remember where. Something about those binding with the plastic.......
I’ve gotten buckets from a restaurant, a natural food store several times, new, and from a couple of other places. No Sam’s Club around here but any grocery stores that sell bulk dry foods in bins usually have them. Reminds me I woudln’t mind picking up a few more.