There’s an old saying, that in theory there’s no difference between theory and practice, but in practice there is. That sentiment could easily be applied to refitting a 3D printer to hold a laser. There shouldn’t be much to it, rig up a laser module to turn on under computer control, mount it to your hot end carriage and off you go. In practice, though there are other considerations to account for. If you have a Monoprice Mini Select, you can start with instructions from [drodrii] for adding a laser to your printer.
Although [drodrii] mentions that you need a second 3D printer to make a bracket for the laser, we think you should be able to print it on the Mini as long as you do it before the first step of removing the hot end. However, since your laser module might not exactly match the one used in this project, you’d have to get it right the first time if you don’t have another 3D printer. Of course, you could remove the laser gear, remount the hot end, print a new bracket and start over, but that’d be a drag.
The laser module used is a 2.5W unit, although you could probably use larger or smaller ones if you were sure the fan output could drive the unit’s power requirements. About half of the instructions are about the software to drive the device and the laser beam focus set up.
You’ll want to wear the appropriate protective goggles should you make this modification. Since laser engraving creates fumes, you also probably ought to operate the device in a very well-ventilated area. You can see a short video showing the machine in action.