The idea of thinning AirTag is very simple. The nature of this toy is to have a broadcast board structure on top of the CR2032 battery, so if you can find a way to spread the battery and circuit on a wider surface, the thickness of the AirTag will decrease significantly. And that is the plan that Andrew Ngai did:
The solution is simple but requires three things. The first is to disassemble the AirTag to get the hardware contained inside, the second is to software design an exact model to hold the hardware, and the third is to use a 3D printer to create a fixed frame. AirTag’s broadcasting circuit and battery. That is not to mention, it is quite sure that if you do like this, AirTag will be denied the warranty. This is meant to be just for fun, but it takes a lot of things to change the AirTag’s thickness from 8mm to almost half, probably not worth it.