Use a garden hose to lay out a circle outdoors on a patio or lawn. A circle 6-feet in diameter is large enough to house two or three children performing a skill or trick.
Whether you're planning or a circus-themed party, or just have kids who love to perform, a large circus ring in your backyard is something you can make with minimal DIY skills. Once the circus ring has served its purpose, use the materials to build or add to a compost pile. Hay bales can also be used to build a small cold box for growing plants out of season when you don't need the circus ring any longer.
Lay hay bales or a 3-inch layer of saw dust around the circle, just outside the hose. The hose is a guide that can be removed when the more permanent circle is in place.
Turn a sturdy plastic bucket upside down in the center of the circus ring to make a platform for performers and the ring leader to use.