Stepping Stone Molds are durable ABS plastic forms for making mosaics using wet concrete and glass mosaic tile. The molds come with rounded corners and a slight taper to make it easier to remove the stepping stones after the concrete hardens. We use thinset mortar mixed with small pea gravel (2:1) for stepping stones, but many people use ordinary concrete. Both are available at the building material store. Stepping stones are perhaps the easiest mosaic project for children and beginners. You can use materials of different thickness because you are pressing the pieces into wet concrete instead of gluing to a rigid surface.