Shooting video hand-held is super convenient, and is a great way to shoot a moving subject without having to frequently move and reset your tripod. Chances are though, your hands are not nearly as steady as a tripod, and hand-held shooting can result in choppy, jerky footage that hardly looks professional.
A Steadicam is a trademarked camera-stabilizing device that allows a camera operator to keep a camera stable while moving, even when walking. And while the name "Steadicam" technically refers to a specific brand of camera stabilization device, the term is also used colloquially for any handheld movement-stabilizing device for a camera. But while a true Steadicam is a heavy, body-mounted piece of equipment that costs thousands of dollars, a cheap DIY variant can be made with parts from a hardware store.
These camera-stabilizing devices rely on weight to make it physically harder to move the camera, which results in smoother movements during shooting. Steadicams also contain a three-axis joint called a gimbal that allows the device to move in three dimensions while the camera stays stable (gyroscopes contain gimbals).
If you're going for the quickest and cheapest form of a Steadicam, don't worry about including a gimbal in your design. Use PVC pipe (metal piping also works if you're really looking for a workout) and construct a sideways "T" shape, using three 12" pipes and a three-way pipe connector. You'll be holding onto the pipes with your hands, so make sure you're able to grip the pipe diameter comfortably.
On the top of this sideways "T," you'll want to have a 1/4" bolt that will screw into the universal binding on the bottom of your camera. On the bottom of the "T," attach a weight. The heavier the weight is, the more the device will impede your movement, which will make your camera movements both smoother and more tiring. Find a happy medium between stabilizing weight and comfort (about seven pounds should be adequate). Install rubber bike handlebar grips at the end of the sideways pipe section and just above where the three pipes meets for hand grips.
If you want even better camera stabilization (and more works and parts), you'll want to utilize some sort of gimbal on your steadicam. A great cheap alternative to building an actual gimbal – it's not an impossible project, but does require more moving parts – is to use a universal joint. A universal joint is a joint most commonly used in car and truck driveshafts and essentially an articulated rod that can "bend" at a joint. The frame of this steadicam is shaped like a "C," with the weight attached to the bottom, and the camera attached to the top. Underneath where the camera is attached, you'll want to attach one end of the universal joint. On the other end of the joint, attach a small section of pipe (this will be the handle). This allows the weight to keep the camera stable, independent of your own body movements.
These DIY methods aren't perfect, and require practice (and some muscle) to effectively stabilize your movements, but with a little time, they'll allow for some great, super smooth camera work well worth $20 and a trip to the hardware store.