Ever wonder why all the iris boxes on Thingiverse have five leaves?

With six or more leaves, the leaves have to overlap each other when the box is opened. That requires a more complex leaf shape, but also opens up some interesting design possibilities.

This 8-leaf iris box can be printed with the upper and lower parts of the leaves in contrasting colors. When the box is closed only the top part of the leaves are visible. As the box is opened the bottom piece is exposed. I printed this with black tops and yellow bottoms, and the effect in the pictures is striking.

This model requires no screws or other hardware, though some glue may be needed to hold the two parts of the leaves together depending on the tolerances of your printer. All parts print without support.

1. Print one copy of each STL file. The bottom pieces of the leaves will only be visible when the box is open, so choose your colors accordingly.

2. Place the mechanism ring on top of the base. It should rotate freely.

3. Snap each of the leaf bottoms into one of the holes in the base, such that the arm engages with the slot in the mechanism ring.

4. Attach a leaf top to each leaf bottom. Depending on the tolerances of your printer you may need a drop of glue to hold it in place, or it may just snap together.