This is a very simple key ring adapter for AirTag. I didn't want to pay for crazy expensive cases just so I could hook my AirTag on a key ring, so I made this easily printable model. I printed mine on a Photon S printer, but it can also be printed on an FDM/FFF printer, just make sure that you have a fine layer height. This model has 5 stars and over 350 downloads on Printables.
(I manually transferred this model from my Printables account)