Rollbe ($18) is a super compact measuring tool, that would make a great addition to any everyday carry arsenal. It allows you to measure straight or curved surface by rolling from one point to the other. Just place the bullet start mark on the starting point and start rolling. Count the full rotations and then add the remaining units. Simple. What about corners. Well, if you bump up against a wall, just add the radius indicated on your Rollbe ruler. The Rollbe 4-inch also comes with a handy leather key chain holder so you’ll always have it with you. Hurry though, because their Kickstarter campaign is running right now and it won’t last forever.