Didn't solder the fittings I used epoxy resin, only soldered the electrical connections and the 510 connector into the cap on the end
The cap on the bottem just pushes on, trick is to very slightly oval the cap with a pair of grips or pliers, and it just stays in place until you pull it off.
Yea the switch was tricky, the one I used fixed from the outside, once I made the connections, just had to carefully persuade it through the hole in the coupling, then epoxied the fittings together.
22mm tube seems to be perfect for 18650's
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