How can I make a hovercraft?

Ever since I was a little kid I've wanted to make one because I saw a TV show where they made one out of a sled & vacuum cleaner plus some other things. Where online can I find the easiest directions to make one that works? I've looked into it a little bit and I'm overwhelmed with 100s of diagrams. I think it would be a cool project for the science fair. I have a brother who is studying to be a mechanical engineer so he can help with building.