Just wanted to share that at last we made a few tests.

With 3.5W+ diode lasers we prove that you can do a laser engraving on painted aluminum and stones.
https://www.youtube.com/watch?v=SjQYrdnWJcs

another useful thing is to do laser soldering
https://www.youtube.com/watch?v=5XXsWwHJqkA

and some useful experiments how to do laser etching too
http://endurancelasers.com/how-to-ma...rom-endurance/

Also remember that you may make your own PCB using diode laser.
http://endurancelasers.com/do-it-you...hing-of-a-pcb/

Hope that you find this materials useful!