Hi Cees, I taught my wife how to help me with the foam core cutting. I'll post some pictures of  foam cutting "Jigs" that I designed to cut out landing gear area so I could drop in and glue a tapered wood gear block in place.  I sold the wing cores with the landing gear blocks installed.  I also sold special contact cement to glue the balsa to the cores.  I believe I was the first to have a water base latex glue for glueing balsa to foam.  A product called Sorgum came on the market many years after I had mine out.  I also had a wing covering material that was better than balsa wood or obechee wood.  I could could wrap my material around the entire wing.  My "Quick Series" of airplane could be built in approximately 20 hours.  Sorry, too many stories. Col. Chuck Winter