That DIY idea has been in my mind from time to time,finally I pull the trigger.
I searched 30+ stores and found this shell, from Convoy,but only grey color.
Do you have better choice?
I prefer 2*18650(26650), and MTG2
I’d try BLF first for research 
hint .
That light you got there is avalible form Banggood for 20ish$: Search “Roche”
I think a good one is the Dipper D19 (37:money_mouth_face: with code also BG. It should come with AR-lens, a good driver. Not that much to do there.
Hello,Dear Online
I know the LightDirect have the material,u can have a look on it,i put the link in the attachment,hope it is satisfied with u 
http://www.lightdirect.net/led-flashlights.html
Your not the only one Rey.
I believe the host is similar to Roche LS01… sold as a complete flashlight at much higher price at BangGood.
The parts arrived yesterday afternoon. It took me a while to assemble the tail cap.
It hardly bounce back until I cut the silicon a little.
The tube seems a little wider for 18650,there's some sound when I shake the light.
Flat top 18650 doesn't work,so I added some soldering on the positive side.
I have a little ocd(obsessive-compulsive disorder) but how to clean the reflector?
There are many ashes on it. I hate it.
There’s no easy way to do so. Is it just small particles on the reflector, or smudges of grease/oil?
If its particles then a can of compressed air should work. Some people also report that using the end of a cotton swab with the cotton teased apart can help dislodge particles.
If its grease or oil, heat up some distilled water in a cup you cleaned with distilled water, wash-out the reflector very carefully with soap and tap water, and then use the hot distilled water to rinse the reflector, so that the residual water evaporates by itself and you don’t have to dry the reflector and risk scratching it.
Thank you. They're just dust I think. I will try compressed air.
I use very hot water and blow it dry with compressed air. If that does not work leave it as the damage from trying to clean it with other items will annoy you more than the original dust problem.