I keep all of my AR tools in a dedicated AR toolbox [little plastic one I got at wal-mart]. Has everything I need in there to build one from constituent parts or to tear one down to it's parts .I did the same thing a few weeks ago looking for my AR Castle Nut wrench. I would have bet you $100 the wrench had a Blue handle.
I looked all over for a Sunday afternoon and could not find it, I was pissed.
Opened my gun junk drawer the next day to get something else, and there was my BLACK handled Castlenut wrench. My brain was looking for a different color and I went right by it before????