Kruder, from The Pathfinder's school, teaches you how to make a spring spear trap with almost all natural materials. This is a very dangerous trap so be warned and be very careful if you practice this. By using any springy tree (he uses a Maple), and a toggle tied to another tree, you can make a trip wire for any sized animal. Add a spear to make it more effective. You'll learn everything from the materials to construction in this video.
Start your career in Graphic Design with the WonderHowTo's Beginners’s Guide to Photoshop Course