It is a mechanism similar to shutter mechanism. There are two leaves. The shape is similar to Chinese Taiji or Tai Chi.When you rotate the Drive Partor the middle plate, the blades inside the center hole can open or close gradually. The center hole's MAX diameter is 30mm, outer size is diameter 74mm and thickness is 8 mm. Most parts are designed for laser cut. The parts' thickness is 2 mm. Most parts can be 3D printed too, it you plan to do that, resin material should be the best option.But the 3d print version may be better.

To assemble the parts togther,some metal parts and glue are needed: 1. Diameter 1mm length 4mm-pin; Diameter 1mm,length 8 mm pin; M2X8 screw; M2 hexagon nut. Refer to the BOM in the attachment. Due to the part's quality, maybe you need to do some handwork.STEP and DXF (vector format) format files are included. Ignore FBX and OBJ format files.