I took that 50W CO2 and made it into an attachment for my CNC mill, it attaches to the dovetail on the ram and has a pretty simple beam path, two turn mirrors into a beam expander, off a Zero phase mirror, an ATFR, a phase retarder, and finally through a objective lens head. I did it this way because I just don't have room for a standalone laser cutter and since I already have a 4 axis cnc mill I just decided to combine it all. I made a separate software configuration to handle the laser and outputs to control the laser, air purge and air assist. The laser itself is controlled from a standalone box that handles the PWM and pulse mode selection.
Full details here: https://hackaday.io/project/177698-b...r-laser-cutter