I lost an NOE 316314 2-C FP/GC mold a while back (.315" 122 gr FP for .32 revolvers). It was in its original box, because I was casting with the HP/GC version after I had used it last.
Couldn't find it, for the life of me, for at least three years. I went through every bin, box, jar, tub, tote, tube, and pile of anything that might be even somewhat related. I just kept coming up empty.
Then, one day, it turned up in a box of carburetor parts.
Apparently, I had set it on the shelf in the garage at some point, and it somehow managed to migrate into the neighboring box of miscellaneous carb rebuild parts (possibly at a very crowded and disorganized time during a rather laborious engine rebuild that caused all casting operations to cease for a few months, and saw many guests digging through my garage for tools that I pointed them towards).
Edit: Thinking back, the 'carb parts' box was exactly the same type of box as the 'bullet molds and handles' box, and they were right next to each other during the engine rebuild. Neither was labeled. I probably did it myself.
When I moved, the box got taped up and wasn't touched for about two years.
Then, when I actually needed carburetor parts last year, I rediscovered the mold.
"So that's where you were hiding. Carb parts. Makes sense..."