This is a magnetic switch that uses cheap whiteboard magnets and standard #10 hex nuts to work. Demonstration:

I originally saw
https://www.youtube.com/watch?v=n9tZIFfM14o
from Andrew Klein and wanted to make my own. I saw other users such as
https://www.thingiverse.com/thing:3556210
had the idea to use standard nuts so it can be assembled at home easily.

This design takes it a few steps further by using space more efficiently to allow more magnets and therefore larger magnetic fields, an internal locking feature, and a snap-fit assembly made entirely of 3D printed parts.

I recommend using a bench vice to install the press-fit part, make sure it is fully seated.

Required Materials:
12x #10 Hex Nuts
https://amzn.to/2ztHLP3

24x 10x5x3mm Magnets
https://amzn.to/2VHKfBW

The provided g-code prints the handle body with supports, this isn't necessary and it can be printed without them if the orientation is reversed.

If you make it post a picture!