Sent to some rancher friends in Texas and other uses occurred to me if modified. A shorter or LONGER tube - maybe larger diameter) without holes could be used for other things. Without a hole in the capped end and if the screw plug were sealed with melted wax it would be waterproof for burying.
A much better and more durable way to make that device, is to get some large Diesel truck exhaust pipe about 4.5" diameter. Cap one end with a piece of 1/8" thick steel plate welded on it, and put your swivel there. For the other end, use a rain cap for a Diesel truck exhaust stack, but modify it to be held closed with a bolt with a nut welded to the side of the pipe. No hog is going to be able to break it open. It may cost a bit more to make it out of steel, but you will be able to put it into your will so someone can inherit it!
@@scottcardwell6387 Go to any repair shop that works on heavy trucks or sells parts for them, they will be able to set you up with everything that you need, except for the swivel joint. But you can make your own if you want to.