For a dimensioned drawing, check out my website: thewidgetforge.com
Step 1: Design
To help with the control issues of an un-throttled engine, I came up with the most unique part of the design: The radio controlled deflector which splits the air between thrust and lifting. It can deflect a maximum of 50 percent of the available thrust to the lift the craft or close off the lift duct completely. While it lets you control the ride height of the craft to some extent, it is most useful for panic stopping by completely cutting off air to the skirt, allowing the craft slid to a stop on the ground.
Steering consists of two balsa uprights which support the two rudders. The rudders are two inches wide and provide plenty of maneuverability, although more rudder surface would probably make it even more maneuverable. A cowling would likely make the rudders more effective too, but the hovercraft is very maneuverable as it is, so it isn't really worth the added frustration in starting the engine to add one.
Materials and Parts
The body is pink insulating foam from a local home center. This stuff works great for this purpose: it is easy to work with and quite stiff on its own. It comes in a variety of thicknesses and usually two foot by eight foot sections. The one inch thick foam is plenty strong for a craft this size. The rest of the structure is made of 1/8 inch thick balsa and, for the engine mount, 1/8 inch plywood from a local craft store.
The remote control system is a two channel set-up meant for cars, boats or other crafts that ride on the surface. It has a range of about 100 feet which is plenty for this hovercraft. The 2 oz fuel tank, fuel lines, fuel, control horns and pusher prop were all bought online at an RC specialty site.