And now for something completely different from my usual projects - a C-Clamp. It has three parts - a body, the threaded part, and the end clamp. The main body has a 2" gap at 100% scale. Put together, it can probably clamp a max of 1.5" (lego guy is 2x scale in the picture, I'd give credit but I'm not sure where I got the lego guy).
One of the pictures shows the slight gap - so the initial setup and anything thinner than 1/8" will need a small spacer to clamp properly (sorry!).
Things to note:
1. I made one before, and the base broke at the thread, along the layer lines after I over-tightened it. That first base was printed on it's side. The second base I printed upright, with plenty of support, and I could not break it by hand tightening it. So I definitely recommend you print the body upright with supports, it felt indestructible even as a PLA part.
2. There are two "end clamps" included. One is looser which I highly recommend, and the other is super tight to get onto the threaded part. The tight one works fine, but you need to really tighten it so that it slips on.