What do the Polish Army, the Special Olympics and the U.S. Secret Service have in common? No, this isn't a joke. The answer is Sam Splint, a thin, foamy material that the above organizations and many others use to make temporary casts for broken appendages. Sam Splint stiffens when it's bent into an arc, making it an ideal instant cast. Invented by Dr. Samuel Scheinberg, an orthopedic surgeon from Oregon, the product weighs four ounces and is waterproof and cutable. It's so light you won't notice it in your pack, and if you're ever unfortunate enough to need it, you'll be glad you didn't have to use saplings and rope.