pls help i wanna make it!
Take piece of paper and fold it like this http://www.paperplane.org/Patterns/sample.html
Aww, you beat me to it :)
build an R/C plane, and then instead of the R/C receiver, install a microcontroller and some sensors. accelerometers, IR horizon sensors… it's a piece of cake these days. of course you should also install the R/C components for debugging and whatnot.
Hobby Lobby and most other hobby stores will have free-flight kits of balsa wood and tissue paper. A frame of balsa wood is constructed from (usually) precut parts then covered with tissue. Balance it properly, paint, wind it up and it flies (and crashes, sometimes).
Even if you don't want to make the kit, take a look at that section of the hobby store to see how the wind-up airplanes are constructed. Worthwhile.