Sometimes the very best souvenirs are the ones you snap in a photograph, scoop out of the sand, or pick up off a hiking trail. I’m not talking about trash; I’m talking about the sand your kids bring home in plastic bottles from the beach, the smooth piece of driftwood you found at the lake, or –as in my case–the five, rounded stones you pulled out of a dried up riverbed while hiking in the deserts of Utah. You and I promised ourselves we would do something with them, and we always want to take something home with us to remember our vacations. Why not combine the answers to these problems? Two birds with one (or five) stones? Let’s turn those rock souvenirs into a super usable and simple-to-make rock cairn door stop.