The orientation thing can be a little confusing. It doesn’t help that the orientation popup changes the selection behind your back sometimes (I think it does this when you click on the world coordinate system indicator, but I’m not sure what triggers it).
The easiest way to keep it straight that I’ve found is to Select X & Y axes. Then, choose two edges of your object (i.e. two edges that are not material thickness edges). That will, at the least, make the Z – the laser pointer – point out from the top or the bottom of the cutting plane. From there, it is a matter of reversing the X/Y axes until the Z points towards where you want the laser to come from.
For a closed box, you can get away with 3 setups as they 3 sets of 2 parallel flat pieces (top/bottom, left/right, front/back). Now, if you want the laser to always cut from the outside, then you’d need six setups (unless you’re opposing pieces are truly identical) so you could have the Z pointing in the right direction on opposite pieces.
It can be tricky to think about, for sure.