I was looking at the marlin firmware source files again. They are very new to me so maybe an expert can chime in but I’m not seeing the mo3 and m05 commands being processed at all by the interpreter.It should be pretty easy to modify the code to process these commands and remap them to the same finctions used by the m106 and m107 codes.
Then your laser would fire with either the m106 or m03. The m03 is definitely better and more cad/cam friendly. If your software allows you to set tool size and spindle speed then you’d be back in business. You’d also have to set the the tool to make only one pass of course.
If no one else volunteers then I’ll try to look into this in the next day or two.