Outline works, but badly I'm very new at Blender but have (or had) a pretty extensive knowledge of 3dsmax.  So I've managed to make this shape, and even managed to do outlines to make it look like a drawing, which is what I'm going for.  But as you can see Blender has taken it upon itself to add some lines where there shouldn't be any, most notably between hole three to hole four. I made this by making a cube and then making a bunch of smaller cubes and then difference-booleaning them out.

Q: Any way to convince Blender that there shouldn't actually be lines where it mistakenly drew extra lines?  Or do I have to paint them out using Photoshop?
This was an wild hunting ... uf :)
The issue comes from N-gon faces generated by the boolean operation.
When model consists from quad or tris faces it works fine.
Solution is to add a Triangulate Modifier at the end of modifier stack like so: