I'd seen a video somewhere on the 'Tube that tested model strength after epoxy application. No pressure application, just straight forward brush on and cure type of stuff. The results were encouraging, about twenty-five percent stronger. Because most FFF prints are not watertight, nor airtight, in a pressure container, you'd get epoxy intrusion right where it can do the most good, in my opinion.

It's an easy enough concept to test at home, especially with the abundance of pressure pots used for resin casting and the like. A common hack is to use a Harbor Freight paint pot and close off the ports.

If you need even more strength, short fiber chopped fiberglass or carbon fiber applied to the model with the epoxy will get you a near bulletproof surface. I fiberglassed a 2 liter soft drink bottle to have a higher pressure horn for my AirZound 2. Four years after putting it out to pasture, it was still holding pressure and never blew up, despite the 120 psi loaded into it.