This is a tough case for your Apple AirTag that keeps it secure and provides flexible mounting options.
Design features
Holds the AirTag tightly and completely protects the battery compartment, preventing it from being unscrewed accidentally.
Front window keeps the antenna unobstructed and shows any engraved markings.
Optional mounting holes fit 5mm tie wraps in horizontal or vertical orientation.
The screws are purposefully on the side with the window, so if you mount it showing the back, it's not obviously an AirTag (e.g., to conceal in your car or backpack).
Bill of materials
You will need two M3x6 screws (the holes are sized for socket heads, but other heads should also fit).
Printing instructions
Choose the version you'd like (mounting holes or no mounting holes).
Print the .stl files as-oriented (the outside on the build plate).
Assembly instructions
Work the screws into the side with the opening first (it isn't threaded, but might need a bit of force if there's some plastic left in the hole).
Place the AirTag into one half and line up both halves.
Screw them together, while ensuring any engraving on the AirTag remains aligned.
Notes
If you'd like a simple modification (e.g., mounting hole size, no window, put the screws on the other side, make it bigger, …) send me a message and I'll see what I can do.