I designed it for

M2 screws + nuts
20x6x2mm Magnets (the same psura used for the Lack enclosure tutorial)

edit: added sacrificial layers to the model in the .3mf file.

I dont have an airtag, although my adhd coach would approve. this was simply a task I set myself whether and how fast I can make a funktional part. the contest was a great motivation because it has a set timelimit to it. I think it could be more practical, less plastic, clickfit instead of screws, keychange link and more. 

but it works as intended: a magnetholder for the airtag.