When you live in a tropical climate it's possible to keep frogs that match that environment outside. Do make sure the temperature and humidity levels meet the particular frog requirement if importing frogs from other areas. As long as the enclosure measurements match the frogs lifestyle (lower for ground or taller for arboreal); the material is a matter of choice.
Think plastic tubs would be fine, since that's the way many breeders keep them in special racks that hold the plastic bins. You can also see how Leonel keeps and breeds his tree frogs in here: http://www.frogforum.net/tree-frogs/...alcarifer.html. A tropical environment opens a door to many outdoor keeping possibilities and lower costs due to no heating requirements.