Make CO2 Ice Cream

Cost: $150
Time: 15 Minutes

Safe | | | | |
Risky

For an illustrated photo how-to, launch the gallery.

Want some real home theater bragging rights? Instead of buying a projector capable of casting a 14-foot image at 1080p (progressive) resolution—the highest high-definition there is—build one yourself. After all, the front projector’s innards are simple: an LCD lit by a superbright lamp, and a few lenses to magnify and sharpen the image. Retail models start at around $800 and use proprietary $400 lamps that burn out every few years. But cheaper lamps work equally well, and none of the other parts are very expensive. Why not put one together yourself?