I use a 10" diameter plant pot saucer or, in my larger enclosures, non-perforated plant seed trays measuring about 12" x 8" x 2.5" deep. These are my preferred. Always conscious of drowning so put clumps of moss or pond weed eg hornwort in, or a flattened pebble ramp. This also serves to provide some hiding places should I miss a couple of youngsters thus reducing issues re cannibalism. The bigger the better really but not too deep. Mine are limited to fit into the main enclosures. As MasSalvaje says, check the dish regularly throughout the day over a number of days.