It's also quite easy to take apart for mods.
Unscrew all the barrel parts.
Remove the switch cap (just use a small screwdriver, that thing pops right out, and it's not watertight anyway).
Then push against the retainer ring around the LED from the front.
First pops out the switch electronics. Then the LED module. Both modules feature a plastic barrel with two halves. Both plastic parts are not glued together and can easily be taken apart. In fact, the switch assembly falls apart very easily. The switch electronics module seems big enough to be easily replaced by something else, like a regulator, a two stage switch electronics etc.
For the reassemble, note the orientation of the switch electronics. If you put it in with the wrong end facing forward, the lamp is constant on.