Updated OP. Chapter 1-4.
Im building a WWII flashgrenade! ...sort of..
Hopefully with 2 driver circuits and some other interesting things. :) .. Hopefully Ill be able to finish too. Not sure of that part yet..
R86`s contest build - WWII Flashgrenade (Finished light in post #1 - Underground pictures and video)
I think its a clever idea this, its original and in the same time it save you from a lot of trouble making all the parts from scratch. I wish you luck with timing.
I hope you have better luck than I with the drivers. Its good to see a start as theres still plenty of time left in the month. Good luck not that you'll need it.
This is starting to take shape nicely - I like the concept! 
Interesting "host" to say the least. You don't think anyone will be scared looking at that when you come walking into a bunker area with that hangin off the belt?
Are you sure your name isnt Mike Crouse and you live in PA? He did this exact “host” but for lasers. Ill grab a photo of it but apparently these hosts are HUGE!!!
Glad you guys find it original and interesting. :)
Hopefully it will work... I have done a bit more work than currently shown in OP, but Im jumping back and forth between different parts. Im trying to release each "chapter" with something finished. Not going back and forth like I do when building the light.
I think its pretty cool using a purpose built "WWII flashgrenade" with a purpose built beam especially for WWII bunkers and such.. :)
MRsDNF, I have two spare drivers in case of ¤#¤&. Now I just need need your time machine so that I can add another two weeks to the deadline. ;)
Nah, thats certianly not me.. :P
Its not that huge... A bit longer than a TR-3T6 with 3 cells. Its got similar head size as a SRK.
I almost considered a bullet build. But that is DBCstm`s thing.. I found them a bit too large.
Seriously, I got asked to build a flashlight out of one.. :D
Maybe another year. Compared to last year im going for the "classical sequel". Bigger, better, brighter, more sophisticated, dual driver, dual switch, tint mixed, beam mixed light and still maintaining an original look while using some new tools (lathe) that I have no skills in using. :D
You can have it. I'll even pay you to take it. The damn thing works in reverse. I'm looking shabier everyday, not younger. As the Toyota ad goes, just do it. 
Good god those shell casings are huge. Are those things made out of brass?
No doubt that your finished light will draw lots of attention around the bunkers.
Good luck in the contest.
I think Dale said the big ones are made with steel. 
Sorry for not replying yet. I've visited a couple time and have been trying to picture where you are going. I really like the concept. Will be another very unique and creative light this year.
Looks like you have a bit of work ahead of you too. Best wishes.
What kind of switch are you planning? A pull switch would be cool. Than you could scream:“fire inda hole” and pull the trigger
Very cool idea for a build. I second the pull switch idea, though I know it will be more work...
I did a bump switch in one light. The weight of the cells provided the mass to compress the switch. Hard bump = on/off, soft bump = mode change. 3 small springs in a triangle to augment the switch spring. Pull switch shouldn’t be too hard but gets complicated by where you put the cells. Good luck on this. Hope you finish.
I could ask if you want to Hi-beam. But id guess they are steel casings too.
I cant compete with you guys when it comes to machine work so Im glad you guys like the concept of the build. :) There wont be much machine made on this light. But since I used a lathe to open up the handle/battery tube, pill have been made on the lathe too (coming in a chapter in few days). Still several obstacles to pass. Im working on the light every day now. Just finished something for the upcoming chapters. I actually started on the light and did the stuff shown in OP early on.. Then I started to do things slower and slower and now time is limited. The build is now on the top of my to-do-list. Hopefully I wont stumble across too many more issues and failures (more about those are coming).
About the switch. I have played with many concepts and various different switches. This being one of them.
I considered various side switch solution and rear switch solutions. And even a combination. It would be cool having something to pull, (load it up with ultrafires and see it blow up) but at the end of the day. I need to easily have control over two driver circuits. This will hopefully become a useable light that will replace my friends Led Lenser X21R for use in bunkers and such. The place where his X21R is mostly used.
I wanted the light to be usable without having to unscrew the tailcap in order to get to a switch. That would be too much hassle the way the light will be used. He wanted it pretty much stock looking, so no switch or drilling through the tailcap. So im going for two side switches mounted on the side of the light. One to each driver circuit. About the same wiring as seen in chapter four.
If you are interested, here is the one that was turned into a laser host
Cool! Thanks for sharing. Now im jealous.
There are several differences between our replicas. Especially the tailcap. How to do the battery tube and tail will be my main issue. Its work in progress. But it wont be anywhere as nice as the machine made stuff done on that laser build.
I dont have the right drill size (only have one 20mm drill) or tools to make an insert tube like he have. And if I had, I probably would not dare. The middle section of my handle is only 28,5mm. I consider inner tube diameter to fit the fat protected 18650 to be 18,6-19mm). If the wall size if the insert tube is about 2,5mm. that would be 19+2,5+2,5=24mm. With the outer wood diameter of 28,5mm that would mean the wood wall on my light would only be 2,25mm thick in the middle section. I would not have been comfortable making it that thin or making a super thin aluminium tube. Im way to good at breaking stuff and not used to working with wood. Not much used to working on a lathe either. 0:)
Hopefully ill compensate with some uniqueness not seen in other flashlights.
very cool build 
Nice work sofar, and an original idea! Hope you get it done :-)