Has a couple of pages on making a pressure pot with AL80.
The pressure pot I had, I made from steel pipe, steel plate and tie rods.
If you don't want to drill and tap into the cut off end of a cylinder you can rig a tie rod setup to hold the top on. Bigger, uglier .....just my style.
Remember that a pressure pot operates at fairly low pressure, like shop air or lower, 125 psi is something like 300 FSW. You can use shop air through a regulator to produce your pressure.
Most things you will pressure check need to be submerged in water, either to check for leaks or to prevent damage to sensors.
The pressure pot I had, I made from steel pipe, steel plate and tie rods.
If you don't want to drill and tap into the cut off end of a cylinder you can rig a tie rod setup to hold the top on. Bigger, uglier .....just my style.

Remember that a pressure pot operates at fairly low pressure, like shop air or lower, 125 psi is something like 300 FSW. You can use shop air through a regulator to produce your pressure.
Most things you will pressure check need to be submerged in water, either to check for leaks or to prevent damage to sensors.