You need: 2 Magnets 10(diameter)x5(depth) like those You can use Smaller magnets.
1x "Left" 1x "Right" 1x "Connector" 1x "Plate"
You can also print the "All" file, it has everything you need. The Plates can hold different sizes of rings. If you have a thin ring, use the small version, etc. The All file has the medium version.
Print settings: Both sides and the Plate need supports. The Connector does not. I recommend to block the supports on the little grove for the magnets since they are annoying to remove. You can just print the presliced All file if you like.
Assembly: Very Straightforward. Put both sides of the heart together and push the Connector through the hole. Then hook the Plate into both sides. Take the pictures as a reference. There are holes in the Top of both sides, that's where the Magnets are supposed to be. You can slide them in if you use the magnets I recommend. If you use smaller Magnets, you will need to glue them.
Tips: Put something like velvet on the plate before hooking in the Ring that prevents your Ring from getting scratched.