Idea is not new, expanders are used everywhere and by everyone, but here it is in the back cover so that all the additional parts are together. those. the only modification that is new here is the back cover, which has its own thread on both side
it turns out that you need to control the flashlight either by turning the head, or by a button in the head
If we need 2 * AA (1.5V + 1.5V), then we connect everything together, putting section C in the middle (there is a center diameter of 15 mm so that the batteries are centered)
if we need 18670 or 2 * 18350, then we connect sections A and B behind the head, and attach section C after the back cover (D)
If we need to use 1 * 123, then after the head we put secuity A (or B), then the back cover and the remaining sections for it
At the same time, the open ends of unused sections have a thread inside, so it will not deteriorate when bumped or dropped. for the same reason, it is better to make stainless steel or thick aluminum
I think that the main application will be 1 * 18670, and depending on the circumstances, it will be possible to use 1 * 123 or 2 * AA
And can also make a short version so that you can use 1 * AA or 1 * 123 or 2 * 123 (1 * 18670) - this section 37 mm + 2 section 16 mm + tailcap section, but then we need to use 2 drivers in one head - 0.5-3.0V and 3.0-8.5V having a toggle switch, or one driver 0.5-8.5V, it is possible, but its development will cost a lot of money
The main minus of this lamp, I see how much metal, that is, the mass, but it is necessary so that you can use different batteries + you can consider it like Yawara for self defense
- if you use it for 1 * 123 for a long time, then wood lice and spider can settle in the rear tubes
in general, the thought came to my mind when I remembered the old game that I had in my childhood, where I had to move an empty cell to get the correct sequence,



