@TL. I may have gummed a few things up, sometimes successfully. 
@RBD. If hardwood was used what sort of thickness would the wood be? Say if the tube was 25mm what would the OD of the wood be?
Yeah... I have seen some of that gummed up BEAUTIFUL work... now we know your secret!!
Have a happy USA Thanksgiving Holiday down there. TL.
I saw one of these in person. They are absolutely beautiful, and I highly recommend them.
Thanks TL and back at our US friends here.
Minimum wall thickness of wood maybe 1-1.5mm. Brass sleeve and epoxy add another .5 mm so 1.5-2mm each side or 3-4mm total + starting battery tube dimension. For example I just measured a Solarforce extension tube at 19mm ID and 25.4mm OD for 3.2mm wall thickness. I could easily match that. With my DIY set up concentricity won’t be nearly as accurate as on a machine lathe though. Probably no better that .1mm at best.
I ordered a couple shorty tubes I thought for the A6 but they only fit my X6. I might be mistaken as I was waiting on the shorty A6 tubes.
Edit- turns out I ordered one of each which figures as it allows me to get woody dimensions on each.
Sorry Steve, to answer your question a tube starting at 25mm with no sleeve would end up at 28mm minimum. Bead blasting might require a slightly thicker wall so add another .5mm for that, actual cuts even more.
No I dont want bead blasting. I love your smooth look on the finish. I was thinking along the lines of a custom light with your handiwork covering the battery tube. I've just got ideas floating around in my head which usually cause me more grief than enjoyment.
how long about your wood handle？the color of the wood is cool,I don‘t DIYbefore ，so I curious about that.
Do you mean how long is it or how long does it take? The one in the op was an UltraFire 502B that was cut and baked to that copper/bronze and lengthened for 2 x 18650 cells. Just the ends of the tube take 3-4 hrs to cut and prep. The sleeve about the same and the wood work a bit more including finishing. I rarely have that much time all at once so it gets spread out a bit. Steve’s idea eliminates quite a bit of work for me but that just means he’s doing those parts instead.
Just ordered a benchtop blasting cabinet and some fine and extra fine grit white aluminum oxide media. Should be here pretty quick as the cabinet’s coming from somewhere else in Ca and the media just up north.
Sounds great! Haven't had a chance to ask my friend about the grit-size in his cabinet. Sorry.
Keep us posted on your findings.
Are you taking on old rusty car parts as well? 
Rufus, that is beautiful!! I love it.
In walnut. 
cute handle!!
For how many cells? 1 x 18650, 2 x 18500, 2 x 18650?
I just think it would look wonderful!
I think many different woods would look great if done well. Solarforce has part of the tube milled as part of the head so either a shorter piece of wood or a break in it. Harder to do but still possible.
Beautiful
On the example in the op the copper is lacquer coated as well so I’m hoping it stays bright. Alp88 would be the one to know though.