I added a bi color led so i could see the laser status without having the laser connected. then I added a 3 pin jumper to select direction pin polarity.
if you are using a dedicated laser engraver this wouldn't be necessary as you could change the polarity of the pin in software. I use my machine for both laser and milling/engraving so I wanted an easy way to match it to the setup of the z axis of the mill.
I have used this circuit with a 2n2222 to drive a mechanical relay, with a 2n2222 pulling a p-channel mosfet, and with a solid state relay. the method you choose depends on your laser system.