Hi Matt, so in this last one that you've posted, this one here (from isodraw):



That's slightly different than what you posted before or what was in Martin's example, because both of those edges are thick in this one, meaning both the red and the blue one I've indicted here:



In your other case you had only one of those edges thickened... With only one thickened the question becomes "which one should it be"... and if it's just an artist's judgement call that's not easy to replicate in computer code.

So I'd probably be shooting for doing the same as Isodraw here and having all silhouette edges get thickened...

Does that make sense? Or is there some specific rule for targeting just one of these 2 possible hole silhouette edges?

- Michael