Goto www.3Dfoamy.com and download some plans

Then order some depron from www.depronUSA.com or get blue fanfold foam from Lowes or HomeDepot and cut out the plans.
Depron is a white hard foam. Its simular to the meat trays that your hamburger from the grocery store comes in. Great for building airplanes.
Get some foam safe Cyanoacrylate "CA" glue and accelerator, and go to town.

Its pretty easy to build one, and they are tons of fun.