This is a model originally made for another project, but after experiencing the fun of it, I developed it into a standalone toy. You need to print the blade board twice to get all the necessary parts. This is a mechanical aperture, and the central diameter will change as you rotate it. I recommend gluing the pins to the blades or fixing them in any way you like, so they won't move too much.

Some people have asked for more instructions on how to assemble it. I've added a schematic of the steps and some notes below to help you.

Step 1: You need a total of 8 blades. You can print the blade plate again, and there are extra pins for precaution, but you don't need two of them. Assemble the pins to the blades, and they should be facing downward. The edges should be flush with the rest of the top of the blades. I recommend gluing these pins to the blades so they can always stay in the right position. Do this for all 8 blades.

Step 2: Place the leaves and pins you just glued into the holes at the bottom. You can start from No.1 as shown in the figure, then move clockwise. The next leaf

Step 3: Using the eight pins erected in the previous step, you can install the next component. All pins should be aligned with the grooves of this layer. You can gently shake it to get everything in place, but they should all be aligned, which will tell you that it's assembled correctly. The "lug" part should be set to the far left while being aligned with the pins. By rotating this layer to the right with all the pins in the grooves, you should see the aperture closing as it rotates. These components should slide easily. If there's

Step 4: Place the final top cover on top and screw the three mounting holes around the perimeter of the baseboard.