Key holder

If you have many keys of different types and sizes, then it is difficult to find a holder for them. Here is a simple solution.
https://www.youtube.com/watch?v=rbjWn5CqxKw
Three printed parts, a metal lid, a 5mm 5mm 2mm magnet to hold the lid, a 20mm 2mm metal rod (optional), a 2.5mm diameter bolt and two nuts to it. The shape of the lid is arbitrary, but it should turn easily and be close enough to the magnet. I am posting STL files for holders of four different sizes, I will add others later.