You had me confused with the thread title. Building from scratch implies starting with a clean piece of paper and perhaps some data like pictures or sketches of a full size then building a plane. Think of how much design, calculating and just plain experience goes into a set of plans. Perhaps you are referring to building from someone's plans or from a kit.

In any case, the advice here is good and building from plans or a kit is half the fun of this fine madness even if the amount and quality of instructions vary. Thank goodness for the local hobby shop or buddy that will let you 'look inside' before buying.

cheers,
quint