fun polystyrene glider

This is my first instructable. A fun glider for your children,younger brother or sister .Or just for your self.Its very easy to make and the best part is that you decide the way it looks , how big it is.

Step 1 Things you need

As you'll notice the pic is up-side down.You need:1 cardboard box or just cardboard(bigger is better) ,1(or more) any size polystyrene tray ( bigger is better), 1 pencil,1 eraser (not shown),1 ruler, 1 sizers or a knife, some prestick,  and a model aircraft book (optinal)