Do you dream of gliding through the air? Then don't miss today's show when Chris explains how to build your own hovercraft. The project is ultrasimple -- your kids can put it together in the backyard.

What is a hovercraft?
A hovercraft is a vehicle that rides on a cushion of air produced by downwardly directed fans, causing it to glide over surfaces.

How a homemade hovercraft works
Air produced by a small blower inflates a plastic sheet. The sheet pushes against the floor to provide a ground-hugging "skirt." This skirt lifts the entire hovercraft.

A small plastic disk (or coffee-can lid) keeps the inflated plastic anchored so it doesn't tear loose from the center. The plastic disk also lifts up vent holes so air can escape into the center.

What you need before you start
You'll need the following items to build your hovercraft:

• One piece of plywood about 3 to 4 square feet, 3/8 to 1/2 inch thick
• Plastic sheet one foot larger than the plywood
• Leaf blower or shop vac
• Plastic disk such as a coffee can lid
• Bolt: 2 inches, 1/4-20
• Nut: 1/4-20
• Two fender washers
• Staple gun
• Duct tape

Caution: Kids, don't attempt to build or operate a homemade hovercraft without adult supervision.

Build your hovercraft
Now it's time to start building your hovercraft. Follow the steps below and consult this simple diagram.

1. Build it: Platform
   1. Cut plywood into a disk shape.
   2. Drill a 5/16-inch hole in the exact center so that the 2-inch bolt easily passes through it.
   3. Cut a hole to exactly fit the hose from the leaf blower or shop vac. Place the hole slightly off-center, about four inches away from the hole for the bolt.

2. Build it: Air cushion
   1. Lay plywood on top of the plastic sheet.
   2. Fold the edges of the plastic sheet over the plywood and secure it with a staple gun about every four inches.
   3. Cut off excess plastic sheeting.
   4. Tape down edges of plastic with duct tape.

3. Build it: Vents
   1. Poke a hole in the center of the small plastic disk.
   2. Place it on the plastic sheet.
   3. Cut six small 2-inch vent holes in the sheet about two inches from the plastic disk. Be sure to keep about two inches of plastic between the vent holes.
   4. Connect with the bolt, nut, and washers.

4. Build it: Get ready to go
   1. Use duct tape to seal any holes and reinforce weak areas.
   2. Flip the hovercraft over so the plastic sheet is at the bottom.
   3. Stick the leaf blower or shop vac in the hole and turn it on.

The finished product
Use your homemade hovercraft on a smooth surface like linoleum or TechTV's studio floor. Just turn on the motor, wait for the plastic to inflate, and hop on to glide around. The hovercraft can support hundreds of pounds -- Chris, Cat, and Roger have no problem riding the "Call for Help" hovercraft.

. When you're tired of gliding, give yourself a few feet to come to a complete stop, and turn off the motor.