Hotwire? My similar idea mentioned on the first thread: tube spars (though it still applies to this). Each air foil is cut through the middle chordwise for a "top" and "bottom" rib half. Stack foam pieces up for ribs, or a block if you want a continuous section. Spar shapes, trussed shapes, holes, etc. can all be cut out. You could cut large sections of foam or pieces of ribs in two shots. Then stack and glue the tops and bottoms together around your spar-and-compression-member-ladder and glue together as a unit. Or glue ribs individually and then slide of the spars and then assemble the wing components. Personally I'm playing with ending up with a completely skinned outer surface but large trussed sections removed internally, and then cover with vinyl. It may require a light glass or dacron covering prior, testing will be done to check the strength of the rib panels. Neat stuff guys, I like this thread.