Whether you want to enclose your AirPods in a waterproof case, a hard shell or a silicone car, there's a case here for you.
Your AirPods came with a handy little case that protects the earbuds during charging and storage.
The AirPods case is fairly rugged to begin with, so I don't feel like you need to enclose it in a mil-spec-rated ruggedized case for safety -- a thin layer of silicone should do.
In a sense, the Mobosi Military AirPods Case Cover is pretty typical -- it's a rubberized case that you slip over your AirPods case, and it comes with a secure mount for a D-ring.
Most cases are soft, rubberized silicone, but the Ztotop Case for AirPods Pro is a combination of silicone and TPU (thermoplastic polyurethane), which results in an impact-resistant hard shell.
The top of the cover uses adhesive to keep it attached to the hinged lid of the case, and it comes with a D-ring that attaches to a hard point on the case.