There are plenty of places that will cut custom wings...

A foam wing if done wrong is more fragile than the original balsa wing. You have ti install spar sections and do some sheeting of the wing core to have decent strength. Even when you have done that... its not crash proof. I've been in a mid-air where the built-up balsa airplane flew through the foam core wing model and it rained bits of styro.... the all-balsa model flew to a safe landing. (it was my balsa plane... it was damaged but easilly fixed. The other airplane was trashed. RC combat gets that ways ometimes.)

If durrability is yor goal... you can just go to the SPAD site and use thier methods to build a replacement wing very cheaply. (about $2) www.spadtothebone.com A trainer wing from coroplast and yardstick is easy to make... takes about 20 min once you have made one before. (1 hr if you have to refer to the directions a lot.)