Read my post on using this to create a self-watering system for my Christmas tree.

https://johnzanussi.com/posts/diy-automated-christmas-tree-watering

The capacitive moisture sensor friction fits into the print, but a dab of hot or super glue can be used to ensure it doesn't fall out.

These 0.31" (7.875mm) magnets are also press-fit into place. I've included the F360 file if you want to modify it to fit other magnet sizes.