AFAIK the Nano that Lummi sells is completely standard. You get an appropriate set of magnets with it to make the battery fit in it. With these tiny cells I'd be a bit worried about the current going into them, but I've not heard of any problems and there are a lot of Rob's lights out there.
Its not that big, in fact its just three 6"x 8" sections and another just started at the moment. Each one took me around 7 hours to complete although not in one session! about 35 mins on a sunday afternoon competes 2 rows (about 1/2"x 8"and starts my fingers aching!) this isn't a project i'm actively working on its just something to do for a small amount of time every once in a while because i have 20,000 or so M8 spring washers (don't ask!) and what else am i going to do with them? 
Eventually all the spring washers will have been made into chain mail hankies (i wouldn't recommend blowing your nose with one unless you are conan the barbarian however) if i have enough pieces i will link them together to make a shirt or coif perhaps.
I haven't used the nano myself but as Don says there are lots of lummi's out there and lots of nano's and the consensus seems to be that they work but keep your eye on them!. I personally have used a cheap CR123A charger from DX (they also sell the nano) and it was ok, charging current was around 180ma iirc a bit much for my liking. These days i use a hobby charger from DX http://www.dealextreme.com/details.dx/sku.12618 at its lowest rate it delivers just over 100ma. i have been looking at getting a coin cell charger like this one http://www.powerstream.com/licoin-charger.htm but for the amount of small cells i have to charge i think i will stick to the hobby charger for now.
Thanks guys.
Well, now I have to ask! (but you don't have to answer if you don't want to). Why do you have 20,000 spring washers?
Oooh you had to ask!
Its a long and uninteresting story and unfortunately your question (or one very much like it) is one i get asked by pretty much everyone who visits us and uses the side door (as the washers are in a lidless box right next to the door) generally just after "what are they?" and "what are they for?" so to cut a long and uninteresting story short... suffice to say i don't like to see anything get thrown away that i may possibly find a use for one day so rather than see them dumped in a skip i took them home and hoped i would eventually find a use to put them to.
On a more flashlight related topic i have so far been unable to find any loose 5mm white led's to try in my Tikey they must be here somewhere! and i am sure i will find them one day but until then i have ordered a few more in neutral and warm tints with various viewing angles and am looking forward to some modding fun 
The split rings! Story of my house. Except in my case it is computers. Probably a couple of hundred of them. Some arrived deliberately and some sorta happened.
You'll be lucky to find any white LEDs with the sheer output of the Nichia GS series. The DX ones in the Photon clones are about as good as any that I'm aware of. Best be might be some of the Chinese AAA lights that have more powerful LEDs in small packages. At least you have a fair amount of diameter to play with and XP-G R5 LEDs can be found on small diameter boards. Don't think there's enough room in there to stuff a 14mm board but there might just be. However, you can forget using 3 LR44 cells for that - it is going to have to be a 10180 and some resistance to keep the current down to something safe. If an R5 will produce respectable light at 30mA you could even keep the button cells. But I really have no idea how much light it kicks out at such a low current. I suspect that the 5mm LEDs may be more efficient at those currents - can't remember the ratings of the hundreds of Nichia LED types and their data sheets are very hard to read.
It might be that Osram Golden/Platinum Dragon LEDs might work better. You can get these quite quickly in the EU from http://www.dotlight.de though their P&P charges are pretty high for a small order. CharlesTT here used quite a few of them on his car though I can't remember his saying where he got them from - might be a good idea to ask him. I think they might be easier to get into the body and mount than Cree LEDs.
Luxeon Rebel LEDs might be an option too. I'd probably steer clear of the K2 ones as they work best at high currrent/power.
Hey Don your almost right i never used the Osram leds in the end as they were TOO bright for the application that i had in mind but i did uses 1w philips luxeon stars that i found on ebay (and they were genuine too) here's another goo place to get parts i get all my drivers from these guys.
http://besthongkong.com/ and some good prices here LED Profi-Shop für Gewerbe & Privat - LED1.de® - Fachhandel
This is using three leds per side... (the white lights at the top)
Don that is outstanding, i don't think i could get away with a couple of hundred computers though! the three i have in the loft along with associated peripherals cause occasional rumblings of discontent
Lots of options there thanks for that a 10180 fits well but didn't make contact with the spring in the tail, a small wrap of wire around the tip of the spring solved that temporarily for testing the Wee LE , 10180 will be the cell i choose if i decide to go beyond 5mm LED's. A 14mm board will probably fit with a small amount of file work or Dremel love but the contacts might prove tricky so im only going to be playing with 5mm LED's for the time being. My goal is to keep the 5mm format but to lose the blue tint and increase flood, brightness is not an issue at the moment as this will only (possibly) replace the standard Tikey on my keyring for keyhole location duty although the standard Tikey seems to be the ideal replacement for my defunct microlight for the amount and type of use it will get (a few seconds per night keyhole duty during the winter months) i am more than happy with it as is. The button cells however are not something i like (at least not alkaline ones) but are no maintenance and as they are cheap enough to replace (50 pack from DX at about £3) i am thinking replacing them regularly whether they are dead or not might be a good idea rather than risk a leaking cell.
My modded Tikey currently has a "Hyperbright" 5mm 18lm, 0.5w, 60mA, 85 degree LED in it and although the tint is cooler than my ideal it has a nice flood which i like in my smaller lights. So far it looks good chasing shadows under my desk and tonight i will put it through its paces, pics will follow in due course.
I also have some more LED's on order, Nichia 5mm Warm White LED, 15500mcd, 15°, 20mA, NSPL500S-E-T-D1/D2 and Nichia 5mm White LED, 44000mcd, 15°, 20mA, NSPW500GS-K1-W-b1/b2 which now i come to think about it is probably the LED Tikey comes with so maybe not the ideal choice but if 5mm's are subject to bin lottery i might get a keeper.
My next move will be to source a few wide viewing angle warm white LED's and maybe try some of Cree's 5mm offerings.
charlestt - very nice indeed! especially the "My other led project" shot, very nice work.
I live alone. Not having one of those "wife" things simplifies life sometimes. My brother hired a skip for me as a birthday present. My birthday was 10 months ago - that is what is left. I really ought to toss the 20 year old Macs and the Suns of equivalent vintage..... And the Sun server that I spent a fortune on and now am not prepared to spend what it costs for the electricity it uses. Or prepared to put up with the noise the 20-odd fans in it make. And that's before I power up the disk array.
10mm LEDs can be ground down with a Dremel then polished with a nylon brush on the Dremel. I used to do this with 5mm LEDs ground down to 3mm LEDs for maglite Solitaire mods. I'll send you a Chinese cheapie squeeze light with a 10mm LED to experiment on if you want. They are pretty bright and floodier. PM me your address and I'll be happy to bung one in the post. The switches are way too sensitive for the things to be useful so most of them I had killed their batteries before they got here. With a 10180 and a bit of resistance they might be interesting. Pretty sure I have a couple knocking around somewhere.
One warning: The epoxy dust you Dremel off smells utterly vile - do the work outdoors.... As long as you don't grind into the die you'll be OK. These are the things I'm talking about:
http://www.dealextreme.com/details.dx/sku.3419
Titanium is very hard - make sure you have loads of Dremel grinding thingies, you are going to need them. For this reason it is a pig to machine.
If you want more flood you can just Dremel the lens end of the LED - get it flat and then polish it a bit with a nylon brush on the |Dremel. It is easy to fix the beam from a 5mm LED
Whoa Don, you had a clear out and still have a house full of old computers... outstanding! fwiw i would not be able to bring myself to throw out a 20 year old mac if i had one, and would probably have to find some way to use the sun server just on general principles even if it meant laying on its side for coffee table duty
Thank you for the offer of a 10mm squeeze light but i'll pass for now (although i may yet take you up on it) i hadn't considered modifying an LED for size or flood and now you have mentioned it i reckon it deserves some more thought as well as some more LED's for testing purposes. At the moment i am leaning towards the 0.5w 85º LED, the tint is cooler than i like but the flood is superb, i am waiting on a few warm white LED's and fingers crossed one of em is a floody incandescent tinted lumen cannon. (well i can dream can't i?)
Titanium is indeed very hard, at work today i stripped out the internals from my Tikey and put it in our small shot blast rumbler for 5 mins expecting it to come out looking nicely dull but it came out looking slightly aged (no pics yet but it looks like its been rattling about on a keyring for a couple of months) but still shiny with crisp edges, 3 mins is usually enough to give an even dull finish on stainless steel so for now it looks like the easy road to a dull rough(ish) finish is off the menu for this light but on a more positive note i showed the Tikey to our resident machine shop guru and explained what i was trying to achieve, his response was a very encouraging "no problem, give me the dimensions and consider it done" so that avenue is open should i not get the desired result with 5mm's.
Now then where did i put that box of Dremel bits?
You wouldn't want this particular Sun as a coffee table, at least not when powered up. I couldn't tell if my (not very quiet) vacuum cleaner was running or not. Think chainsaw noise levels. Bolting some legs to it would make a reasonable coffee table - it is a metre long and 19" wide. 7.5" (4U) deep with a handy storage slot for two 3.5" hard drives like everyone ought to have in their coffee table. Its former owner was the London Stock Exchange who probably paid around the price of my house for it. They sold off around 200 of the things in 20 full size racks.
The plan was to get a bunch of Sun Ray terminals which are fanless and diskless but couldn't get them at a sensible price.
Don, chainsaw noise level is something i try to avoid in my coffee tables
On the left is a warm white LED my phone cam got pretty close with the colour, it is only slightly more yellow than what i see by eye . On the right is the original Nichia LED after some scotchbrite love (thanks Don, i hadn't considered modding the actual LED until you posted), the blue tint is less noticeable and of course its more flood now.
The warm LED is a keeper and will hopefully provide many years service as a keyhole finder/light of last resort.
Here are a couple of shots to show the effect 5 minutes of shot blasting had, not the desired satin/dull finish but it gives it a certain worn look
A week or so keyring duty for this one
Do any of you guys own both the ITP A3 and the TiKey? I would like to see beamshots comparing them. I got my ITP A3 and I was very surprised at how small it was. Always thought it was more bigger. Puts out a nice amount of light. Very bright on high with 10440 but gets hot in seconds.
Any more news on the led upgrade ??
No news as such, it is still just about light enough when i get home from work that it isn't needed yet but it has survived on my (somewhat overloaded) keychain and shows no more sign of wear than it did fresh from the shot blast :)
a shot showing what it has to contend with
and an attempt to show its current state of wear (apologies for the poor image but i couldn't find my gorilla pod and had to try and hold a torch at the right angle while holding a jewellers loupe in front of my mobile phone cam) to my eyes it actually looks less worn than it did fresh from the shot blast! possibly due to the rough edges of the craters being worn away
EDIT:- Forgot to mention, i received some Quantum Tunnelling composite (I can't wait to drop that into a conversation) from mutr.co.uk and have been having lots of fun turning my single level twisties into infinitely variable lights including my Tikey, it was pretty cheap at 15p per 4mm square but they have a £10 minimum order it is lots of fun and indeed has some very practical applications for instance my 10180 eiger #3 power level (which was a little too bright for my liking for night time house navigation) is now spot on perfect :)
It's been a while, but here you go:
TiKey and A3
TiKey is on the right on all three pictures. Both lights are 52mm from the wall- I used the lenscap to position them.
A3 low
A3 Medium
A3 High
