Always wanted an airsoft gun but never could get over the cost to buy one? In this DIY video, you'll see how to make a fully-automatic airsoft gun using a soda bottle and compressed air.

(Related: Meet the man who builds amazing giant slingshots -- and see them in action)

Check it out:

Materials for this project total about $15. SlashGear explains the design:

The concept is simple; you pressurize a soda-bottle full of airsoft pellets and give the air only one way to escape, through a barrel, out the cap and, ultimately, into a target. The assembly process is simple as well, requiring only that you drill two holes and mess around with a little hot glue. It’s child’s play.The result is a jurry-rigged device that completely justifies its appearance within mere seconds of use.

The creator of this YouTube video has several how-to projects loaded on his channel and blog, GrassRoots DIY, ranging from homemade fireworks to how to raise a pheasant and other chemistry projects.