I've been using rubbermaid tubs, but may switch to 5 gallon buckets.
Today I watched my faithful layer, my cuckoo Marans, go around a small coop, under a big growth of blackberries, past a couple rolls of chainlink fence and behind the hay barn to find an old 5 gallon bucket laying on it's side. Followed her back there, it took me 20 minutes to hack all the black berries away so I could get there. Sure enough, two pretty dark brown eggs! I'd wondered what happened to her egg yesterday.....if she likes them so much, I may start using them in the coop. Much easier for me to get to!