The hardware store sells inline water filters. They have a screw on cap about 5"dia with .5"-2" threaded inlets and are rated at 125psi at 100f. The one I was looking at is twelve dollars and is made of polyethylene and polypropylene and there are others made if better plastics and has a full capacity of about two liters giving plenty of room for 1L of reactants. My friend tested it with an o2 wacker at 80psi with an orbit shaker but o2 wacker failed but it worked well as a vessel.
Yes, That pic really is me!