Some time back my brother built the Guillows 500 series Messerschmitt. He builds plastic models so this was his first balsa build. I did not help him with this build and I think he did pretty good. He built the kit per the plans with no mods. His goal was to build it and fly it since the box says can fly with rubber. He covered it with kit tissue and used a glue stick. He covered in the sections as described in the plans. He then applied 2 coats of dope and applied the decals. He used Testors wood cement to glue everything together. He did a great job of building it nice and straight, I was impressed. Still needs work with covering skills, but this takes time. He made three mistakes that made flying this bird impossible. 1. The prop was on backwards. 2. He never balanced the plane with CG. 3. He used the rubber that came with the kit. So his plane did not fly and he was disappointed and asked for my help. When I saw his plane I told him good job on finishing it and building it straight. It weighed in at 34 grams without rubber or clay. Once I balanced it, the weight was over 40 grams. I told him if I were to have build the same kit with the wood, it would have weighed the same. I told him at that weight it is best not to fly it since it would probable break on the landing. Now he is building the Guillows easy Mustang kit.