Relevant Video

These little 30mm wide round clips are a fun functional example of compliant mechanisms.

The single part flexes to act as a reverse action gripper. Use it to clip papers, bags, or whatever you please.

This download includes the same clip at 3 different wall thicknesses: 3mm, 4mm, and 5mm. I found 3mm to be strong enough for typical uses but it may be informative for you to experience the effects of different thicknesses on a compliant mechanism like this.

I printed mine with MatterHackers PRO PLA at 100% infill. PLA will lose clamping strength if left in the open position for a long period of time, especially at higher temperatures. ABS, PETG or ASA may be suitable options. Leave a comment if you have success with another filament!