I use a round melanine bar tray, about 1-1/2" deep and 14" across, but I've got adult tortoises...for your youngster, a terra cotta or plastic plant pot saucer will also work fine, and they come in various sizes.
For a very small (young) tortoise plastic container lids work well for water and food dishes. The type that are found on yogurt containers and similar sizes. They have low sides that enables a baby tortoise to climb in and out of easily without being trapped in the container (especially in the water dish), but enough of a side to hold shallow water and some of the food in. The water will sometimes evaporate sooner in these shallow containers if too close to a heat source or if the enclosure is too warm overall. But it can also be used as a very good indicator of overall dryness within the enclosure. If the water evaporates rapidly, within a few hours the enclosure is most likely too hot and dry. If the water remains throughout the day the moisture/humidity level is probably suitable for the tortoise. I don't like using the terra cota saucers or similar depth containers with babies until they get to be at least a couple of inches long. The rim is too high on them and the water depth is too deep unless you fill it with small stones to decrease the depth. in deeper containers baby tortoises can easily overturn while climbing and and out.