It's possible to have it so you could use variable voltages on the laser with relays, such as one voltage for etching, another for testing/targeting your piece. And because my idea is to have the laser stationary and have the material moving, it might be possible to implement some cooling so you can use 6v. But the other thing is to have a lens to focus to a tiny dot. That way you can have multiple settings by just adjusting the height of the lense in front of the laser... or at least that's my thought. I wonder if it's possible to get it working... worm gears maybe..... Oh well, when I can afford it, I'll let you guys know when I'm building it.
Actually yes, you could make a few lemon batteries if you have the right material.
Also, it's one of those because I can moments.