About this 3D model

This is a Belt Block-X used in UP! printer. It has three functions, blocking the X-Belt, locking the cable and triggering the photoelectric switch. *The teeth on the model is to intermesh the teeth on the belt, so the belt can be blocked. *The projecting teeth like parts is to lock the cable. *The long and thin part which is painted green is to trigger the photoelectric switch. Why paint it green? Since ABS is a little transparent.