This is a filament spool clip in the form of a clamp that can generate a surprisingly firm grip. The filament it is printed with must be extremely strong and able to flex slightly. I used PETg, which is ideal for this application.
This design is as much of a test of the strength and flexibility of PETg as it is an actual useful filament spool clip. Printed in PETg, it takes about 16 pounds force to open the clamp all the way, so its grip is quite strong. If anyone prints this in a material other than PETg, I would like to know how it compares.
I printed this with supports under the overhanging parts, with support structure dimensions set to 2mm.