This is a picture of some handmade guitar picks (plectrums), posted by a member at MAKE.com. They are cut from gift
cards,  credit cards, hotel room keys, etc. Some are made from other materials like cardboard, "Handi Snacks" stick, CD, Toshiba laptop, and plastic
packaging.

These picks have more mojo than a store-bought pick, but you might find them a bit disappointing when it comes to trying to play with them. Although if you make enough you are bound to find a material that is just right for you. I experimented with a pick made from a credit card , but I prefer a Dunlop Tortex pick (purple flavour).