I've done this just hot-gluing the rim around the top of bottle caps over the 1" hole. It works great, and I don't see it working itself loose.I had a preliminary test going. The primary problem is... while the INNER diameter of the tops of the water bottles is 1", the OUTER diameter is actually ~1.5mm wider than an inch.. Cuz the outer diameter isn't 1", it won't fit into the 1" hole I cut into my enclosures with a hole saw. I guess I can still just glue the bottletops directly onto the surface of the enclosure but I can already see the glue weakening over time as the bottle caps are screwed on and off. Perhaps an expoxy or plastic-specific glue needs to be used to create a chemical bond. This presents a following problem: exposing our T's to toxins I don't know. I'll figure out a practical solution eventually!