Parallettes / Safety Racks
I got this idea on Crossfit. I used the basic Parallette design to create a Pillar of Poverty. Loaded with 655 pounds they are rock solid. Additionally I, at 205, stood on the bar. Again they were rock solid. I made 2 of the wood bases a little longer than the Parallette design. Pictured above the upright pipe is 16 inches. This is of course adjustable with different lengths of pipe. It might not be as quick to change heights, compared to the real thing, but it sure was cheaper! Compare, if bought all retail, approximately $70 with a variety of size uprights to $400 plus for the real thing.
To quickly get the uprights even with each other, put the safety device flat like shown above and make sure all four ends touch the ground. This is also a good reason to keep 2 of the boards the same length. This makes a long project very quick, when changing sizes of uprights.
For additional stability, you could put weight, sandbags or plates, on the wood. I haven't found this necessary, but as the uprights get higher, it might be a nice safety idea.
REVISED
Important note: It is very important to use a pipe wrench to get all the joints tight. This will make the unit much stronger. Also use the long uprights as leverage to get the top pipe as tight as possible. The pipes are designed so that some thread will almost always be showing. They normally can't be tightened down until the treads disappear. The quickest way to change the upright height is to use the pipe or wood for leverage to get the bottom loose and the use a normal wrench on the reducer. I have reducers tightened down on all my different lengths. This is one reason to use a reducer, it speeds up the change. I used an 1 1/2 inch pipe as the upright, a 1 1/2 elbow, and a 1" reducer, then 1" pipe for the rest.
I ended up replacing the wood with pipe. I used a 12" and a 6" pipe on each section. It is even more solid than the wood, especially when using longer uprights. The metal also makes the bottom heavier. The wood would still be fine, but I had pipe available. It could also be cemented into a bucket etc, if your not going to change the height.
The unit has turned out to be a lot more versatile than expected. With higher uprights, it makes an excellent dip unit. It's rock solid and the angle is adjustable. Readers have reported using units for bench safety racks, bench racks, squat racks, squat safety racks, etc. It's nice to toss short bars on for various lifts. It can be used for hang cleans/snatches. It has MANY uses.
Happy Lifting!