This is pretty cool. You could get really creative and the Legos coming apart to collapse the frame would probably help lessen the impact of low altitude falls. Although, it would get pretty annoying to have to rebuild after every hard landing.
http://www.geek.com/articles/geek-cetera/flying-lego-drone-built-out-of-quadcopter-remains-20121220/
http://www.geek.com/articles/geek-cetera/flying-lego-drone-built-out-of-quadcopter-remains-20121220/