This tool looks like some medieval nasal torture device, but it’s actually a handy spring clamp for holding small miters together. You can operate it easily with one hand — Ulmia builds the handle right into the clamps, unlike other wire spring clamps that need separate pliers.
In Germany, Ulmia makes these lightweight 3″ by 1-3/8″ miter spring clamps from high-grade hardened spring steel that provides a constant clamping force. The ends come pointed to minimize damage to the miter, and you can easily resharpen them.
You’ll pay $6 each for these spring clamps.