Getting the rails right fixes most problems.
I've had success duplicating my result, scaling it up, then using the original to cut out the inside from the scaled outside.
I also had success using the "Surface" environment (not the Model environment) which I later turned into a soild, but I expect you could turn it into a surface with a given thickness instead if you wanted.
If you're molding with expanding foam - beware that it exerts significant pressure - a thin skin mold is not going to work right I'd expect - long things like wings are quite floppy direct off a 3D printer.
I recommend my add-in for the foil shapes - I've done 8 years research on airfoils found around the internet - long story short - they are all garbage: vastly too many non-experts worshiping anecdotes have resulted in a flood of rubbish that is simply wrong. NASA themselves literally have the last word - this is their final addendum to their NACA series:-
"Today, airfoil design has in many ways returned to an earlier time before the NACA families were
created. The computational resources available now allow the designer to quickly design and
optimize an airfoil specifically tailored to a particular application rather than making a selection from
an existing family. "
That's the verbose way of saying "Do not use any of our foil families".
Fusion
