Cheers, I'll have to have a play with it a bit (lot) more and find a way I'm comfortable with. I spent a lot of time this afternoon in CATIA making a nice surface model then ended up with a 40meg STL file and was kicking myself for not realising it was going to end up unusable, even though it should be obvious!! Cheers for the tips guys, I suppose like most I'll have to find the way I'm most comfortable and take it from there !