Originally Posted by jetlag

The fiberglass will bend 180 degrees, but it won't have any elastic ability to close the gap created by the amount of travel as the wings unfold. Not sure what you could use.
What about stretchy thin, wide elastic, attached latitudinally (along the hinge line)? One can buy it from Walmart in the sewing section. You'd have to glue securely to each side of the hinge; might even need to 'preload' the hinge material. Glue to one side, let dry. Then, stretch it slightly and glue...secure with pins and let glue on that side dry. It may be a tad thick, but should work.
You could even 'sew' a piece of elastic into place...just zigzag the stitching between the two surfaces to be mated. We used to do this with stick-built airplanes back in the day.
Or...
Use a piece about 3/4 wide and as long as the chord you need. Cut alternating flaps in the elastic and glue to the upper an lower of the two mating surfaces. We did this with stick-built control-line airplanes for their control surfaces back in the day.

Allen