It is a special box or a functional unit. When you drive the handle(or the bolt), the blades open or close gradually. It is not lightproof，and it is not a gear reduccer .br You can design the bottom box by yourself and then assemble it other parts by bolts.It can be considered a gift box design plan.br To assemble the box, you need to prepare some metal parts: M3X12 screw, M3 nut, M3X10 screw, M3x16 screw.