Summary

I downloaded couple of c-clamps, but unfortunately were failed prints. The issue is always with the threads. Too tight. I decided to give it a go and design one. I wanted to design simple fast, but working. So, here it is. I designed it using tinker cad in less than half an hour. If you haven't tried tinker cad before, you must. It is easy, free, and straight forward. I used to design in freecad, but it is tiresome, with a long learning curve.

Print Settings

Rafts:

Yes

                                            <p class="detail-setting supports"><strong>Supports: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting resolution"><strong>Resolution: </strong>                     <div><p>0.2</p></div></p>                                                                                <p class="detail-setting infill"><strong>Infill: </strong>                     <div><p>100%</p></div></p>                                                    <strong>Filament:</strong> Sovo PLA                Yellow                    <br>                        <p class="detail-setting notes"><strong>Notes: </strong>                    </p><div><p>I used a raft to better stick. If your bed is well aligned, no need. I resized it to 50% and still it works.</p></div>

Post-Printing

                <p class="detail-title"><strong>Just clean and use!</strong></p>

How I Designed This

This is how to create threads easily.
https://www.youtube.com/watch?v=1Osx9BZafJI

C clamp resizable, print in place