I use several 4" pvc pipes with end caps glued on for vacuum tanks.
Been using them for years. Cheap, and they work good for us. They run
about 25 to 27 inches of vacuum.
Our shop has a central vacuum pump, and each machining center has a
vaccum tank for a vacuum chuck system. the tanks allow the colant to
seperate from the air, and not get back to the main pump. You could
smack them with a hammer, and nothing (bad) will happen.
You can drill and tap into the end caps for the fittings.

I will repeat this here too.... Do not use PVC for air pressure!!!
Pete