what glue should i use when making 5, 12 V connectors (plugs)?
Well, duh.  I forgot about the so-called liquid electrical tape, which is just a paintable rubber that can be had at most "big box" stores.  I had some once, but it long ago hardened beyond usability.  So I'm guessing that would be pretty good stuff.

At any rate, the 5 minute epoxy tested as open circuit, so I'm going to use that, since it'll save me a trip to the store in these covid-19 times.