I have had good sucess with my LED “15w” laser and using powder coat powder mixed with alcohol. I just used regular rubbing alcohol and mixed with powder coat powder (i used baby blue) until it’s about milk viscosity and painted it on a piece of aluminum with a foam brush. I let it dry and hit it with around 50% power and around 100mm/min (don’t remember exactly, shoulda wrote it down, doh!). Afterward, just washed off the rest of the powder coat with water and it worked great.