I recently published a modular holder system working as a very versatile 3rd hand for any delicate task you may encounter: https://youtu.be/XsCk5LUepSI  , https://www.thingiverse.com/thing:7329310

Here you will find the files for the various versions of clips I designed using clothespin springs.
There are two clips types, with and without central pivot, and each type has 3 variants with different jaw geometries (large teeth, small teeth and rod). Each clip has a 8mm rod handle, compatible with my modular 3rd hand system.
The version without central pivot is the simplest to print and assemble but it is less reliable as the two sides of the clip can close at an angle.
The version with central pivot uses a 17mm M2 screw to go trough the spring and hold all the parts together. I personally find it much more convenient. In a pitch, this model is passable even without the screw.

Both types require the spring of a 60mm clothespin. That's the cheapest and most commonly available around where i am but you should make sure you find the right type... The clip version without central pivot will be more forgiving if your springs are a little different.

You can print those clips horizontally if you really want to save time and maximize resistance but i prefer to print them vertically with fairly dense parameters  (4 walls, 25% infill) in PLA+. That takes longer but it is strong enough for anything that relies on the strength of a clothespin spring and the jaws and rod come out better. Just be generous with the skirt and printbed glue if needed.

Edit: I added one version without 8mm rod handle but that can attach directly to a 8mm rod with a M4 knob. It is the equivalent of the "Clip_aligator_metal_close" from my modular system: https://www.thingiverse.com/thing:7329310