A special structure that converts rotary to linear motion or linear to rotary. There are 3 pins. Parts are designed for 3d printing. Resin is the best material when 3d printing. You can cut off the guide part if it is too long. And to use this structure, maybe you need to make some change on the design.STEP format files are included. Ignore FBX,STL and OBJ format files, they are only used to meet the platform’s requirement.More mechanical models: https://youtube.com/c/DTomsen