Circular truss is fun! We created a circular truss piece that could be raised and lowered between horizontal and vertical positions. We used it for a four week series, and changed the position each time. One time, we actually moved it during the course of a song for a unique effect. We created a screen across the interior of the circle using spandex, and projected on it using projectors that were hidden by stage boxes that matched our drum and keyboard risers.
