I have been working a few years to design and build a practical, efficient variable capacitor for amateur radio loop antenna. The goal is to use 3D printing and easily available parts. See my other projects: the HF short loop antennas and the easy-peasy high voltage variable capacitor. They provide a background for this project.

This project is complete. It works very well and is my primary portable antenna. See the photos. I have not written it up yet as a step-by-step project.