Finally getting around to testing @mathew 's clever ideas around sealing up plastic water bottles as electronics enclosures!
The basic idea is to leverage the technologies already perfected by the 'home brewing' community (and by chemists ...), and use a mechanical, gasket-like seal between a rubber stopper and the edge of the water bottle mouth. Mathew discovered that a 'number 2' stopper seems to fit inside a typical (20 mm diam) water bottle mouth.
- Here are the stoppers I purchased on Amazon (about $2 ea).
The other advantage of this approach is that it gets around using adhesives directly on the plastic of the water bottle; water bottles are typically made from polyethylene, which is hard for most stuff to stick to very well (a nice feature for a drinking container): instead, we can use adhesives inside a hole drilled inside the rubber stopper itself (or on other materials we might use in further gasket configurations inside the stopper, like tubing.
I was in a rush last week to attempt this idea, so I simply took the adhesives available on my desk, took some wires -- and then, at the very last minute, a temperature probe -- and tried sealing them nicely inside the rubber stoppers. I let them cure over the Labor Day weekend, with the idea of deploying them asap.
I'll be trying these out in water bottles today sometime -- will post pics of the configuration ...