Most of the lasers discussed on this site are CO2. You can only cut organic materials and acrylics with CO2. 12mm solid wood is on the thick side for typical lasers. If you do get the power to blast thru it the edge quality will not be great. I guess it depends on what the part is suppose to do.
if you want to cut metal, fiber laser cutting machine is suitable for you. but if you want to cut wood, the best choice is co2 laser cutting machine. the two machines have different feature.
you can check the following video for cutting 12mm wood