A hovercraft is a vehicle which travels across land or water just above a cushion of air provided by a downward jet, as from its engines and propellers. It finds extensive uses for sports as well as military purposes. Commercial hovercraft can carry passengers, vehicles, and freight. Some can travel as fast as 130 km per hour. You can not definetly make such a vehicle, but you can make a model that illustrates its principle of operation.
It's rather easy. All you need is a waste compact disk (CD) (The disks that are used to dispense computer software, games, music and films), a discarded PET bottle (the kind that is used to dispense soft drinks, cooking oil or drinking water), a big balloon and some adhesive.
The method of construction is as follows:
Cut the head of the PET bottle along with its cap with the help of a hot knife. Remove the plastic ring, if any, used for sealing.
Fix the bottle cap in the center of the CD with the help of the adhesive an epoxy adhesive e.g Feviquick, is the best. Fix the balloon on the bottleneck that you had cut.
Drill a hole, about 4 to 4.5 mm in the cap.
Inflate the balloon through the bottle neck and then screw the bottleneck into the cap. Alternatively you can screw the bottleneck beforehand and inflate through the hole in the CD and bottle cap.
Place the CD on a smooth table top and watch how the CD moves across the table.
If the balloon is large it may bends sideways acting like a brake on the floor. You can prevent it by making a paper sleeve (like the one shown in the picture on the left).