A little bullet shaped device that can help you quickly pull a drawstring back through the hem of your clothing.
I sliced this at .15 resolution in Slic3r for Prusa, and it came out too weak. I set the "solid infill threshold area" to 25 mm^2, and that fixed it. If you print it at .2 resolution, it shouldn't be a problem.
Just glue the tip to the body with some super glue.