I needed laser engraver, but didn't wanna buy one to save space in my rental apartment. Instead I've got a 5W solid state laser module and installed it on my Delta Printer. Since my delta printer using magnetic joints - I can swap between laser head and 3D printer head in a matter of seconds. This mount with a set of 6 countersunk magnets replaces standard K800 magnetic effector (like the red one on picture).
Magnets (12 mm countersunk)
Laser module 2.5W
Best value for the money!
Laser module 5W
Faster and cleaner cuts of thicker materials!
TLL input is a must have
Otherwise it will be harder to control laser exposure. Without TTL input you can only vary the speed of laser trajectory. Which might be not enough for some some scenarios and hard to tune to the required level. Connecting TTL input to colling FAN output MOSFET you can control laser power setting fan speed (M106 Sxxx and M107 G-code commands). Please refer to details on this page: https://electronics.stackexchange.com/questions/321987/convert-12vdc-fan-controller-output-to-ttl-signal-of-laser
And DON'T FORGET protection glasses
For a blue laser you need green color
If you do home PCB DIY - the laser engraver is absolutely must have thing for you. Because it helps to accomplish different stages of PCB manufacturing:
At low power setting you may use blue laser to expose copper layer pattern directly to photo-resist film applied to copper clad. No need to print templates on clear plastic projector film and then struggle with variability of UV lamp distance and time of exposure. I also had to print two mirrored templates and precisely align them together, since having single layer of ink-jet ink were not enough to properly block UV light. Exposing photo-resist dirreclty with with laser can give you resolution of 1/10 of mm or more (google for LaserWeb tool on GitHub). It is better when done by low power lasers, they have nicer circular spot, I had to back-focus my 5W laser by 2 mm and still use minimal power (4..5%) so that low-power defocused spot doesn't burn photoresist and actually cures it, the spot is still small enough to give me 0.10 mm traces (see my pic of PCB in the develop solution).
LaserWeb tool (https://github.com/LaserWeb/LaserWeb4) is ideal for the purpose to combine path routing and raster operations together (for traces and copper-pours respectively).
If you still don't wanna hustle with laminating photo-resist film to your copper clad and its development in caustic soda solution - you may skip these going slightly dirtier way, but still using a laser. Just spray paint your PCB with black acrylic paint and then burn the negative pattern with a laser at high-power setting. Vaporizing the acrylic paint is less precise than exposing photo-resist at low power, but for the sake of simplicity you may trade off the accuracy.
2..5W laser can cut plastic films that may be used as SMD-stencils to apply solder paste on PCB pads. To get clean cuts without curling of plastic drop a white paper sheet on top of the plastic film and spray it with water. Wait for paper to soaked and swipe-off the excess water with a credit card (yeah, sorry, you need a credit card here). Water-soaked sheet of paper on top cools down the plastic edge immediately after laser slit through. It also helps to absorb laser energy when cutting clear plastic films. Without paper it almost impossible to cut clear plastic film, yellowish kapton however absorbs laser light quite effectively and burns fast, still need watered paper to prevent excessive curling on cut edges.
- Finally - 2..5W laser can cut colored acrylic and plywood. It can't do clear plexiglas for the very same reason of energy absorption vs its dissipation ratio. On a picture - I've got a solder-paste applicator setup for one of my PCBs. SMD-stencil for solder paste was cut out of clear plastic film used for projectors. A jig to hold custom-shaped PCB was cut out of 1/16" black non-transparent acrylic sheet (the same thickness as of PCB). Absolute satisfaction of using this (did like 150 boards in few hours).
UPDATE June 11 2019
Attached an image with steps and diagrams to locate the G(gate)-pin of the FAN MOSFET to be used as TTL signal source. Download an image in original size to view the details.
ABS plastic is recommended from durability standpoint. In case laser cooling fan malfunction PLA may overheat and melt, however it is more likely that the laser will die before that happen.
Scale the part accordingly to the shrinkage factor of your plastic when it cools down.
Press-fit or glue countersunk magnets into the part.