Build a cutting laser from an old PC
 

[Drake Anthony] makes building a cutting laser from a PC look easy, and it seems like it actually is. Almost everything you need can be found in a dead desktop unit. The diode is pulled from a DVD writer (16x or faster), with the power supply unit, and heat sinks from the processor and GPU being used as well. You’ll also need a focusing lens (just a few dollars), some thermal glue, an LM317, a resistor, and a pair of protective goggles matching the laser diode’s wavelength.

http://hackaday.com/2010/09/30/build...rom-an-old-pc/

You can also try blue-ray laser diode, seems to be even more powerfull ;-)