I Like the strap/ handle that holds the lid on, but the elastic I'm afraid might loosen up if I use it actually as a carry handle. The main reason I was looking for a carry container was to not have dust /debris falling into my vehicle during transport. I think I will try a heavy duty garbage bag initially. All beer keg tubs and garbage cans are In the 16" to 18" diameter range at base, so no go. The 17 gallon steel tub from home depot would probably work, but as you noted no lid makes it much less useful. Plus, it weighs 5 pounds, so 30 lbs w/firepit. But, hmmn, maybe I'll check if the steel tub, upside down would be effective as a winter cover while on my deck. It would not keep moisture out as effectively as a snap on lidded plastic tub, but may be a decent substitute.
We have been enjoying using our propane firepit on our back deck. We pretend we are camping. It is a pleasant reminder of 'almost' feeling like we are camping. )