[morzh]

>>>The hot glue serves as an insulator (along with heat shrink tubing) to accomplish that.

A noble cause indeed

Here's how I see it:

1. Cut  a circular piece of dense paper (backing from a sticky notepad etc) diameter of the can. Should fit in the can snug and definitely be larger than the cap itself.
2. Make a hole in it for the top cap's conductor to go through before you bend it and route it down the can to the positive pin. You could cut a little notch in the cardboard circle for that wire to easily go where it should without having to bend the cardboard. Make the conductor protrude a bit through the center hole in the washer so the hot glue catches on it and thus stabilizes the cap a bit. It is not the kind of assembly that is subject to vibration so you do not have to be overzealous with the stabilizing. Just so it doesn't bend due to gravity back and forth.
3. After assembling everything put hot glue on top.