Our 6W setup is the same one in our instructables, except it has a 6W laser diode instead. Also I changed the encoder placement from the Z axis stepper to an independent hybrid nema 17 stepper motor, but I'm still using Z axis commands to control the intensity. You can see it in the video I posted above.
The 450nm 6W laser diode was purchased from DTR here: https://sites.google.com/site/dtrlpf/home/diodes/6w-nubm44-445nm-laser-diode
The laser driver is the same Flexmod P3 we used in our instructables. It will output a max of 4a. That's a safe max amperage for the 6W laser diode.
I don't think the 450nm wavelength will etch glass even at 6W without painting the surface black first. The black paint causes the laser beam's focal point to be real intense at the surface. This causes the glass to fracture below the paint and so the laser beam does not just pass through the clear glass.
The air assist we developed for our Shapeoko can be made on a lathe. It was turned out of black Delrin and screws onto the laser's lens thread and tightens up on the laser module to seal it from any air escaping there.
Here is a quick sketch of the one we made for our EmBlaser. The hose barb's tight angle was required so the air hose would exit out the top/rear of the laser shield. The one we made for our Shapeoko did not require as tight of an angle for the hose barb.
We also tapped the tip of the air assist for a 10-32 SS set screw with a .040" orifice through hole for the laser beam and air to exit. We run it with a 10PSI regulated air pressure from an oil less air compressor.
We don't sell laser systems or components, only software to generate image engraving raster gcodes for CNC machines and of course, a reliable gcode streamer.