Any ideas on making a cutting disk or bit to make 0.2 mm grooves? Answered

I'm trying to find a easy way to put in slots in a guitar fretboard, which requires really small slots cut into hard wood. Cutting with a saw takes too long so I am coming with a device to help me make fretboards faster. However, I tried making a cutting wheel out of sheet metal which burns the wood and wobbles too much and a cutting bit is too wide. I plan on using a motor. Any ideas on solving this problem?