If you use a foam core then you can just use a hot wire cutter on a template of whatever profile you like.
The RC plane folks are coming up with some really nice methods nowadays, just look for "Airfoil Foam Wings" on youtube and there are plenty of videos. Obviously you want fins, not wings, so make the airfoil wing, then cut from it the desired fin design, and the airfoil will still be there.
There's a guy that does not even use a hot wire, as he can make perfect airfoil wings with foamboard, razor knife and hot glue gun. He has a method for folding the foamboard that works well, and could be tweaked just a little to get a symmetrical foil, as you don't want an airfoil that generates lift on one side.
Here you go:
[video=youtube;qJZoqGHAIDE]https://www.youtube.com/watch?v=qJZoqGHAIDE[/video]
Again, make the wing, and remove whatever shape you need from it. Then paper, glass, cf or "other" it.