While certainly no substitute for a proven water purifier, this DIY water filter from a plastic bottle works in a pinch. The layers of gravel, sand, and charcoal remove sediment and impurities.
There are many ways to use plastic bottles for survival, including this DIY water distiller by desertsun02. It is straightforward to build and doesn’t rely on a stove like most homemade water distillers.
These fish hooks by John Yost are gorgeous. They are made by carefully carving down a portion of deer jawbone. The result is a sturdy hook that works much better than those DIY soda can tab hooks.