Tetherball Sets, Poles, Balls, Courts, and Other Gear
Standard Tetherball
A tetherball is much like a volleyball, except that it needs some way to be attached to a rope. The attachment comes in two types: a loop protruding from the tetherball's surface or a bar recessed below the surface. I recommend the second type. The protruding loops tend to break faster, and when they get hit, they hurt the player's hand. The recessed bar is a little harder to get the rope through, but hitting the reinforced part of the tetherball near the bar hurts less than hitting the loop, and it's nearly impossible to hit the bar itself.
Tetherballs vary quite a lot in how soft they feel when hit. Players unused to the harder ones often find them unpleasant. If you don't have much experience with different balls, the Super Soft type (available via the "Tetherballs" link here) is probably your best choice.
Even though the tetherball doesn't weigh very much, it exerts fairly strong forces upon the pole. The thin, lightweight sectional poles that come in some tetherball sets are not up to the task. They wobble so badly, they ruin the ball's flight path, and eventually, they bend or break. If a set contains a heavy-duty sectional tetherball pole, it might be adequate, especially for smaller players. The best pole is a 12'-long, 2"-outer-diameter, steel pipe, sunk 2' into the ground. You can get such a pole at a plumbing supply house. An eye bolt, run through the pole 4" below the top, will provide an attachment for the rope.
Dig a hole 2.5' deep, with a 2' diameter, pour a 6" footer, let it set, then set a 2' piece of larger pipe in the hole with something to keep it in place while the surrounding concrete sets. The larger pipe should provide a fairly tight fit for the tetherball pole it will hold, and it should protrude just enough above ground level to keep soil from falling in, yet not high enough to be hit by a lawn mower, if relevant. When the pole is removed, a small cap to keep debris out is a good idea. Make sure the ground pipe sets up perfectly plumb.
Although the most common site for a tetherball court is on a lawn, heavy use will turn that area into mud in short order. Extra driveway space can make a great site, as can a gravel area, both of which make it easier to play while the ground is still wet after a rain. Falling should be very rare for most players, so a hard surface should be safe.
No outer boundary circle is needed for the court, because there's no advantage to getting very far from the pole, but it's best to have at least 8', preferably 10', of clear, level ground all around the pole. The only boundary needed is a line dividing the court into two equal halves.
One setup that is definitely unsafe is using some kind of a portable stand as a base. While tetherball players rarely fall, they constantly jump, and coming down on the edge of the stand will almost certainly cause an injury. I have seen portable stands used in supervised indoor paddle tetherball, but intense vigilance is required by the supervisor, and this choice is not recommended.
The rope's length should be set so that the bottom of the ball ends up two feet above the ground when the rope is not wrapped and the ball is at rest.
Paddle Tetherball
Commercially made pole, ball, and paddle sets do exist, but usually people just use old tennis balls with a rope poked through at about 10:00 and 2:00. The best way to make the holes in the tennis ball is with a power drill and a 1/2" bit. Hold the ball in a clamp while you drill. The bit can slip off the ball easily, so you don't want your hand in the way.
The only difference in the pole requirements for paddle tetherball is that a lighter pole might do, because the ball is so much lighter. A portable base is still unsafe. Set the lighter pole in the ground if at all possible.
Paddle tennis racquets make great paddle tetherball racquets, and Jokari paddles or aluminum junior tennis racquets will do. Racquetball racquets work well, but they'll wear out quickly hitting the heavier ball and, occasionally, the pole. A wrist string should be worn with any kind of paddle or racquet to keep it from flying out of the hand and hitting someone.
In paddle tetherball, the ball flies fast and sometimes unpredictably. It's also small enough to injure an eye. Wear eye protection. The type used for racquetball will work perfectly.