I've modified free plans from http://www.foamyfactory.com/ for a faster build that is also stronger.
This requires just 1 foam core board that can be purchased from a craft store.
I used the 1/2" thick board instead of the more common 3/16" version I've used in the past.
Step 1: Airframe Layout
Put the design on poster board so you can easily trace out the design for future builds.
I've found that making just the vertical profile of the fuselage, the whole wing and the tail is all you need.
Trace out the designs on the foam board.