Michael,

>I see - but how was it that you noticed in Powermill that some surfaces were reversed in the first place, does it show some kind of indicator or coloring of the object side in there? If so then you could use it to do the direction tuning.<

They show up in a different colour. You can flip then in Powermill, easily done, but It should be done beforehand. Just for the sake of customer satisfaction :)

Customer are fickle, they like that sort of attention to detail...