An easy two part magnetic tray. Simply print both parts, glue your magnets into the centre recess (make sure the polarities are all facing the same way!) and then glue the cover over the top of the magnets.

The magnets I have used are 20mm x 10mm x 2mm. I used a total of six magnets as you can see in the images. I would not try to use thicker magnets as the cover will not sit flush when you glue it in.

Enjoy!