I'd like to rig up a glass pressure vessel to see if I could demonstrate crush depth and stuff like that. I was sort of picturing a large small-necked glass jug (think water cooler jug) filled with water and attached to a compressor (or maybe even bike pump?). Styrofoam objects would be inserted, weighted down so they are suspended near the middle of the water, the top sealed, the vessel pressurized, etc... I've seen demos like this done with Styrofoam beads in a plastic bottle filled with air pressurized with a bike pump. Since liquids aren't compressible, would filling the glass container with water first make it impossible to reach sufficient pressure? Thoughts? Safe? Fittings? Could enough pressure be generated with a bike pump?