I guess that if you want to totally scratch build a plane then you need a cad program to design one by. An Idea of what you want the plane to look like and be different from any other out there. Then the tools to fabricate the parts from basic balsa and aircraft plywood and foam. Then after all the cutting and sanding, you build the plane. Thats a lot to expect from a scratch builder but I know several guys (including me ) who do it. Time invested will never be paid for by money. Pride in a job well done cannot be priced. However there are several kits and ARFs that can satisfy your building instincts. That is the reason for all the ARF, RTF,Kits and products out there. This hobby has it for anyone or everyone that wants to persue it. Cost of doing it all ... Who cares? It is the pride and the satisfaction that is reward enough.