This is one bodacious project that I first heard about on the MAKE Magazine Blog. It’s creator has a site that tells the story of how he spent a total of $15K and 2 years to build it, but the results speak for themselves:

There’s the laser cutter in all of its glory…

A “Lazer Fish” made from sheet metal. A gallery of some of the artist’s other laser creations is here…

I’ve seen other homebrew CNC lasers, but they were all of the much lower-powered (80 watts and under) “marker” variety–suitable for some engraving and cutting wood or plastic, but not really capable of cutting sheet metal the way this bad boy does. Like most laser systems, the lasre itself is fairly bulky and remains stationary. A moving set of mirrors is used to direct the beam onto the target. In order to cut, oxygen must be fed to the target as well, and a fume hood made of clear plastic pulls away the smoke and fumes from the operation.

In addition, the laser itself must be tightly focused in order to achieve the necessary power density for metal cutting. Such optics are not inexpensive:

Two sets of optics were tried. The newer set is at the top and is more compact…

Coherent G-100 CO2 laser was $6500 surplus…

There is a tremendous amount of detail about the project on the site. If you’re interested in lasers, it’s well worth a visit!