Sounds like a fun project, can I assume you are powering this lift with man power? or do you plan on hooking up some sort of actuator? Keep in mind that a scissor lift will require you to have a track for 2 of the 4 legs on the ceiling and that may require some metal if your looking for the best performance. If you are looking for simplicity, and to make it out of wood, I might recommend a cantilever lift.