All my planes are scratchbuilt from Coroplast. Hinging is just a matter of cutting away one side of a flute. US Air Core also uses Coroplast and are hinged the same way. We've designed a very simple hinging tool, so the Coroplast hinges are made in seconds (as fast as you can pull the tool) http://www.spadtothebone.com/SPADT/hingetool.jpg