All my designs & progress available @ Marginally Clever Youtube video Stewart Platforms are used in flight simulators, CNC machine equipment, robotic surgeons, and connect the ISS to the space shuttles. I call this model "rotary" because it uses a rotary action to move each "arm". a linear platform would use linear actuators. I designed this so that university students can stop reinventing the wheel when they need a platform - get one of these, contribute to the open souce design, and help make life easier for everybody. If you use one of my designs, please let me know! I'd love to see what you make with it and share with others who are interested.