So after a lot of talk, I made my slosh tube yesterday. I got an 8' length of 110mm PVC pipe and two end caps. I cleaned it up, cleaned the last 1-2 inches of each end with fine emory cloth, then cemented one end on. I stood it on the ground next to our front porch (which is 2-3 feet off the ground) and leaned it against the railing and poured water in from a bucket. I found that enough light shone in through the sides that I could peek in and see the water level. I measured the length of unfilled pipe until the water was about 2/3 of the way to the top. I then cemented the other end cap in place.
A friend said that the cement only needed a few minutes to be strong enough to hold pressure. I don't know if that was just wrong, or if I didn't prepare the pipe well enough, or if I didn't put on enough cement, or if the cement was old or what, but when I was done, both ends leaked! Bummer!
I live in Papua New Guinea, on a mission station that is an hour drive from the nearest town that has building-supply stores, and I used the last two end caps from the stock room at the hospital's maintenance shop. I tried applying more cement around the seams to see if I could still get it to seal. I'll work on it more this afternooon.
The original blog by Dan John mentioned his tube as 9' long and weighing 38#. Since mine weighs (or did before all the leaking) 24#, I assume that his is also 4 inch diameter (about the same as my 110mm). I thought that I should make mine smaller than his, since it's a good bet that he is considerably stronger than I am (sarcastic joke here).
I played with it in the yard, trying to clean it, and to rear-squat it. On the clean, I could not really get a clean grip on it. I managed to get it to my shoulders and squatted once. On the second try it tipped. Once it starts going it is very difficult to control.
Today I'm a lot more sore than usual. I worked out yesterday afternoon, and did a little bit of a few things that I'm not used to, but not enough to account for the amount of soreness that I have.
Soreness is not the goal, but it does indicate that some muscle had to work more than it is used to working. I'll keep working on the tube, and reporting the results.