This thread clamp is fully 3d printable with no supports, glue, or cleanup.
Check out the videos for assembly instructions and a clamping demo.
All parts of this clamp can be printed with standard settings, but if you want it stronger, print the knob.stl at 100% infill. Also make sure to apply wax to the threads for smoother turning.
See it in action:
If this clamp seems useful to you consider downloading my upgraded version. It has more reinforcement and a smoother turning thread.
I also have additional grip pad designs available for $3. They work with both the free and upgrade clamp versions.
You can also find my process for designing this thing here.