Homemade laser engraver

Hi I'm in the process of making my own laser engraver out of some old scanners and printers which I found easy enough to do. The part I'm stuck on is what size laser diode to buy and what driver (Circuit board ) I would require to run it all I can find the stepper motor boads on ebay but nothing to drive the laser though my computer hope this makes sense and any help much appreciated thanks anthony

If you found a stepper motor controller for say a 3D printer with 3 axis of control perhaps you could use the axis for up/down movement to trigger the laser? I assume a laser engraver only needs up/down left/right movements.