These tiny versions of my compliant mechanism clips are only 15mm wide and yet they're functional! It's an easy print, no supports required, works right off of the bed.

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 or ASA, and PETG may be suitable options if you need to maintain the original strength over time.

Relevant Video