Spread a 1- to 1 1/2-inch layer of marbles or pea-size gravel in the bottom of a 2- to 3-inch-deep container if it doesn't have a drainage hole. Put coarse sand or a commercial potting mixture formulated for cactus and succulents in the dish, stopping 1/4 inch from the top.
Remove each cactus from its nursery container. Wear gloves or use a pair of tongs to avoid the sharp spines. Create a small hole in the dish -- just large enough to accommodate the cactus' root ball -- using your hands or the tip of a trowel. Place the plant in the hole, then pat the potting soil around the roots. Repeat for the remaining cactus plants.
Spread a thin layer of coarse sand or tiny rocks on the top of the soil to add interest and keep the cactus dry. Add figurines or rocks to your cactus dish garden, if desired.
Water the newly planted cactus garden lightly, adding only enough water to barely moisten the soil.
Place the container in bright sunlight in a warm, dry room.