Slap a motor and a few servos on a piece of cardboard and you've got yourself a model airplane. Sometimes I'm surprised how easy it is to get something flying.
I work in the UAS industry and we absolutely do use things like these cardboard airframes for prototyping. They're awesome out of the box and really easy to repair with some tape and hot-melt glue if necessary.
Slap a motor and a few servos on a piece of cardboard and you've got yourself a model airplane. Sometimes I'm surprised how easy it is to get something flying.