I am just starting working with foam for RC planes but have done lots of work with foam mockups in my job. Usually this is with foam core board (with a paper skin on both sides, usually 1/4" thick).
Having done several searches on this and other sites - and not found much basic information on forming things out of foam sheets - I thought I might start my own "resource". Hopefully others, with more airplane experience, will add their methods.
The image is a sketch of the most basic corners I have used. Although they are drawn with foamcore (paper skinned) in mind, non-skinned foam would be worked the same way, although packing tape, etc. would help.
Probably the most interesting method is the last one shown, using multiple diagional slices to make a gentle curved shape. Try it, you'll like it.
Allan

Nice post!

I wonder how it would work if you gave the cut surfaces a light misting with water and a very thin coat of polyurethane glue (i.e. Gorilla glue or cheaper alternative) before bending? The water mist will "kick" the glue so it will cure fairly fast. I suspect that the resulting curve would end out much stronger than the original foam. The PU glue will foam up and fill any voids giving a very good bond. PU won't attack polystyrene foam. Have to use a minimal amount of glue or you would be carving off the excess after it hardened.

Ross

Thanks for the nice comment, MinnFlyer. Your graphic posts have always set a high standard of clarity and artistic merit so a compliment coming from you is worth a lot.
On the gluing idea, I am intrigued. I want to try some similar things with foam when I get some time (after I finish my current project).
Allan

Real usefull
thanks[sm=thumbup.gif]