How to build a laser in the garage? So I wonder if it is any how possible to build laser at home. A powerful one to melt brick.
 A: The DIY aluminum foil approach if you have a HV supply:
http://wiki.4hv.org/index.php/Nitrogen_TEA_laser
http://www.sparkbangbuzz.com/tealaser/tealaser7.htm
http://www.repairfaq.org/sam/lasercn2.htm
This is based on the TEA approach with nitrogen from the air (or from other sources) as the lasing material.
A: I believe that the answer to your question is no. Of course if you order all special components like resonator mirrors, high voltage power supply, etc., then it doesn't matter where you build the laser. But you cannot build a laser with items from a DIY-shop. 
And just a remark - there is no way to melt a brick with a laser. Ceramic plates are very heat-resistant and they are used when you need to block a high-power laser beam (not a trivial task).
A: You don't need a laser to burn holes in a brick; instead, concentrate the power of the sun using a giant fresnel lens.
A: Yes. 100W CO2 laser is doable at home, and some in fact did that.
100W one will BURN really well.
No other types of power lasers are doable at home. (well, probably there is also killing 200 DVD-RW drives and collimating them all - I am actually doing that, I have 45 RW drives ;-) )
The only problems is that you still need few rare things like IR mirrors & transparent window which are very hard to find in garage (there is not much materials transparent at 10um). 
Probably the optimal solution would be just buy finished CO2 tube from China (100-200$) and build cooling & power supply system by yourself. This is way way more realistic.
