In these two videos from the Flite Test R/C plane channel, the guys turn the pizza box their lunch came in into a pretty respectable R/C plane. Just add motor, battery, ESC (electronic speed controller), and R/C transmitter.
On the Flite Test site, they offer plans and complete build instructions. As they point out in the flight test video, some people may have a hard time getting the kind of foam board used in a lot of DIY R/C plane builds. But what hobby nerd doesn’t have a pizza box or two laying around?