I use them for so many different things. Besides mini first aid kits*, sewing kits for Mrs. Rookie and my daughter, I use them the way my father and grandfather used baby food jars. Nails, screws, smaller drill bits or screwdriver bits, things like that. Eventually, hopefully sooner than later, I want to line some of the C&D/Pease style tins and keep camera lens filters in there in my camera bag. And I'm definitely taking inspiration from
@PipePint&Cross for ashtrays.
*I'm on blood thinners. That means, for cuts and scrapes, I usually am one level of care past most people. What you'd let air, I use a band aid. What you use a band aid, I'm using gauze and tape. And so on. So round metal tins are packed with rolls of gauze and electrical tape (man-daids as my wife calls them) are tucked in cars and desk drawers and kitchen drawers and fishing and hiking gear.