I got this idea from MOTAT in Auckland, Ministry of transport and technology or something like that. http://www.motat.org.nz/
Synchronicity was I had made them at home then saw them same day on t.v. and its been a year since i first saw them at MOTAT. I wonder why they came up twice in one day, then i thought i should share the idea also its so simple.
You need a pump style water bottle lid, a cd stack plastic cd or a record, some blue tak or glue. and balloon and a clear surface like a table or bench top.
When you buy a whole lot of cdr the first cd in the stack is just a plastic one these are perfect.
Attach the pump water bottle lid to the middle of plastic cd or record over the centre hole with glue or blue tak make sure its air tight. Close the lid. Blow up a balloon attach it over the lid, then pull up your lid opening and tap the hovercraft in the direction you want it to go, the escaping air will propel your craft.
You can even race them.
you could try cardboard if you have no record or plastic cd but it needs a hole in the middle. I wonder if a cd would work it might be too heavy.
Such a simple hovercraft - i might try it in the bath today or the paddling pool instead of the bench.