If you're thinking about adding a projector to your home, DIY site Instructables has a step-by-step guide on how to create your own functional projector for much less than you would ever pay retail.
To begin the project, you'll need a large cardboard box (a cereal box will suffice), a fresnel lens, a magnifying glass, a LCD, a round cylinder, aluminium foil, tape and scissors.
The box needs to be cut and modified so that the light and lens system works properly within it. After placing the lens in the appropriate place, the light will have to be sealed to keep it from escaping. Once that's done, attach the LCD to the projector. Instructables has the whole detailed guide available below.
If you've got any other interesting DIY solutions, let's hear 'em in the comments below.
DIY Homemade Projector [Instructables]