I guess we’ve all seen the hovercraft made from an old CD, a balloon, and a squeezy bottle top (you haven’t? Instructions here) – next up in complexity is the foam-tray-and-propeller variety. Here’s a nice write-up of one such design at Instructables.
It can be tricky to get hold of suitable motors and propellers in the UK, but your local branch of Maplin will likely have something usable.
If you try making one, point a camera at yourself doing so and send us the result. Obviously.
(ed’s note: woohoo! First ‘proper’ entry!)