In 2015 C.J. Chivers and his teenage sons drew a plan for the beginning of an outdoor home gym. First came racks that turned into a pullup bar, wallballs, and a climbing rope with a set of rings 16 feet off the ground. Plates, kettlebells, and a tractor tire soon began to follow. While some people playfully teased the family, calling it a prison gym, Chivers had come to appreciate the box-gym style. Now the gym is used by his older sons as a workout space, but his younger children and their friends view it as a pirate ship or volcano.