Most cacti have shallow roots and grow slowly, so choose a shallow container. You don't need a deep pot or a very large one.
Spread a layer of small pebbles or gravel in the bottom of your container. Top it with some potting mix designed for cacti
With your cacti still in their original pots, experiment with arranging them in the container
removing the cacti from their pots. Slip on a pair of thick gloves to protect your hands and use tongs to gently ease out the plants
No gloves? Fold layers of newspapers or a piece of lightweight cardboard into a thick band. Wrap it around each plant before you handle it.
When your plants are in place, use a small trowel, spoon or other tool to add more potting mix, gently firming it down.
Lightly water the cacti. Wait until the soil dries out before you water again. If you overwater, they may rot.
Put a layer of decorative pebbles or small stones over the soil, or add some miniature figurines. Use the tongs to move the figurines close to your prickly plants.