SPAD means Simple Plastic Airplane Design. It's a very inexpensive, yet very effective way to build planes. The home of SPAD is found at the SpadToTheBone Website

There are several of us who are building with plastic (coroplast) including Robert Geiger (the original site SPADster) and several of his desciples (Leo, Jerry and a couple others).

We highly recommend plastic for durable trainers, sport and fun fly planes that are a lot of fun to fly. These planes cost typically less than $10 in plastic material for a whole plane. Building times are measured in hours and days in stead of weeks and months. Best of all, when you crash one of these planes, you can often just pick it up, dust it off, start it up and fly it again! Sure beats ending your flying for the next two weeks while you rebuild!

Additional resources include:

Harbor Sales - order plastic from these guys. Look up Coroplast in their on line catolog. Remember, the flutes are the tubes running through the plastic just like in regular cardboard.

...I'll update this document with more sources soon.