As Mark showed, sometimes it's the actual tool, but in many cases it's the jigs to better utilize the tool, as Neal said. A couple of weeks ago I was going to turn something on the metal lathe, needed a particular tool that I don't use too often, opened the cabinet, took out the box it was in, and did what I wanted, but spent the next hour or so wondering what those things in the bag were. It was one of those small ziplock type bags, the size of a sticky note, with something like a 1/4" or 5/16" washer that had been cut in half. Hmm, I knew they were there for a reason, even remembered cutting it in half and filing the cut edges down to size, and would have known exactly what they were when it was time to use them, but what the heck for? On to other things when I remembered they were miniature spanner wrenches that I can hold in a pair of pliers while recalibrating the feed screws. That's only necessary maybe once every ten years or thereabout, but invaluable when it's time to do it. So there are all sorts of custom handmade tools and jigs in hundreds of thousands of garages and shops, some easily recognizable like push sticks, tenon jigs, etc., etc., etc., and some not so recognizable like two halves of a flat washer.