A few weeks ago I went to the mini maker faire in Stockholm and I wanted to show of the laser. Due to safety concerns I couldn’t run the laser out in public, but to be able to show of the CNC capabilities I built a penholder.
It is a quite simple build made out of wood, some plastic from an old cutting board, a few screws and a 9g servo. The servo is controlled by an Arduino, when the signal that would normally turn the laser diode on is high the servo is set to an angle that pushes the pen against the paper. The design was inspired by the brush holder on the WaterColorBot by Evil Mad Scientist. In their design the pen is lifted up by the servo rather then being pushed down like I did it. I don’t know what is best but it works both ways.