Originally Posted by rjw
People with ball machines need a much different solution than those without....
rjw, in your quest for info on building a DIY pressurizing tank you may find some useful ideas by searching for "build your own pressure test vessel".
You will get hits on discussion boards of guys who are building similiar devices to test electronics to be used in scuba diving.
I am pretty sure you have more engineering knowledge than the average TT poster here so I don't have to tell you to pay attention to the cautions regarding the potential burst energy of pressurized gases.
Good luck with your quest and stay safe...