I should also have mentioned - within the EU such a chamber would fall under the scope of the Pressure Equipment Directive.
Fortunately when the working fluid is a liquid that is neither explosive, flammable, toxic nor oxidising; then the chamber would fall into the 'Sound Engineering Practice' catageory as long as
Working pressure < 1000 bar
Working pressure x volume < 10000 bar.litres
(full description is slightly more complex)
It therefore MUST NOT be CE marked, there is no requirement to involve a Notified Body in reviewing the design or inspecting the finished item.
The 'manufacturer' is held liable under the Pressure Equipment Directive, so anybody with any experience of pressure systems would probably want to know the categorisation of the chamber and see some design calculations, or know which code it is design to meet, before they would undertake producing such an item.