Interested in 1.
IMO, it needs to start moonlight>low>high
I don’t like being blinded while trying to access the lowest setting on a light.
My suggestions
Good tint, good CRI. A good tint is higher priority
Go easy on the glue for emitter swapping.
Use more colors other than black for aluminium body
Modes: Moonlight [1lm] / Medium [15lm] / High [60lm] plus hidden turbo[>120lm] and SOS/beacon mode
If it has a button than add shortcut to access hidden firefly mode [0.05lm] mode as well.
I’ll be using it indoors most of the time. I’ll probably get (3) or more for gifts if the price remains and the UI is tweaked.
I have Astrolux M01 but it’s low is too bright and it’s been unreliable as a gift light so I’m in need of something better.
I also like rechargeable, and 10180 lights offer that, and I like that size. I just found the switch mechanism to be finnicky, and the modes not to my liking, hence my interest in Quantum Tunneling Compound, like Peak uses.
Sofirn could just offer that basic 10180 planform, and enhance it for BLF with a nice High CRI LED, and a pressure ramping brightness
I propose E21a 3500k w QTC in a Ti 10180 size
Agree on the switch - like your idea
Interested in one
It goes without saying it needs to be waterproof. Warm and hi CRI. That means different LED options because people are all over the board. I don’t suspect you can have any sort of user-friendly button switch anywhere on anything as small as what most people are thinking about. 40-43 mm. So it will be just like the Acebeam M50 that already has 3 different led options. That is fine as long as it offers other LEDs other than the Acebeam. Edit. I already have the Olight i1r. Other than being a little too cool white, I’m quite happy with it. 5 low and 130 high lmns. I’ve carried it daily for over a year but it is not my primary light. I suspect that some of the people that want it to be bigger with more options/switches want it to be their primary light.
I, also, carry an Olight i1R (neck lanyard). Not my primary light, either (that’d be an S1R-II or FW3A). Agreed that it’s too cool of a tint, but decent otherwise.
Something like this but rechargeable?
good info
yes, that 10180 format, but with QTC and Ti
yes 
size is dependent on battery choice
the 10180 w USB keychain lights all share a god awful 2 mode reed switch… get rid of that and use a qtc instead, and we would have a unique product that is unlike any peak, and unlike any other 10180 light
I agree that QTC would be cute.
A little announcement: it will be aluminum to keep costs as low as possible, but stainless steel and titanium versions are possibilities.
sb56637 I hope that good knurling will make it sufficiently easy to use one-handed, including for lefties.
pooptoast The RovyVon A series are quite nice, but their biggest downside is the high cost. How did yours die?!
Noir Awesome response! Great points, and I especially appreciate the great detailed reasoning in line with the goals of this light. I agree with many of the points. Some probably won’t make it though, such as USB-C, LVP, and regulated output for a light in at the target price point.
For the wear concern with aluminum, what do you think of hard anodization (Type III) without dye? There would be no paint to scrape off, so it would not look as ugly if scratched. Plus the “natural” look might be appealing to some. Personally, I think this could strike a good balance between wear resistance and low cost.
What is the reason for visually linear brightness spacing? Especially with only 2-3 levels, would it not be better to select them for use-cases? Actually, I have a proposal on this subject which I may share later. 
jon_slider Thanks for dropping that link to the historical small lights! A modernized Drake with built-in charging would be a good target here.
As for QTC, that’s really cool! Though I do have concerns about cost, long-term reliability, and usability. An video I found demonstrating its use showed it was rather finicky and sensitive especially on a small light. I think that would get frustrating, particularly on a tiny light.
Scallywag Personally, I agree with you on color temperature and tint being more important than high CRI on a keychain light. On the other hand, there seems to be a fair bit of interest for CRI, plus it would be a distinguishing selling point since not many other keychain lights have it. The eventual selection is likely to be a common use emitter like the the SST-20 4000K, which seems to strike a pretty good balance for what various people want.
Muto, Th558: Yes, perhaps a different version would be good for those who want a bigger battery, but aren’t there already such options? Although the 10280 is intriguing, I’m not sure it distinguishes itself enough from either the 10180 or AAA.
shirnask The goal is as tiny as possible with the features mentioned.
flightless Yes, reliability is key! That has been a big concern of mine while researching keychain lights.
Oli I presume it will have O-rings for water resistance as most of them do. A glow in the dark O-ring under the bezel would be a nice bonus. As much as some don’t like twisties, it’s hard to find an alternative that is as simple and reliable. As for the Acebeam M50, its custom 10150 battery is a deal killer for me. Just why…
Interested!
Interested in 1 thanks!
Good ano might be an issue, anything keychain related usually gets a thrashing after a few weeks.
Cheers!
Quantity I would buy: 5 (if side switch and price below $10 and 2x10440 or 2xAAA) 
Suggestions
Switch: Side switch
Emitter: CRI SST-20 4000K (like the C01S)
Reflector/Optics: TIR lens (like the C01S)
Charging: built-in micro USB (plus cable)
Battery: As big as possible (2x10440?) but sealed to make the light as tiny as possible. Make it possible to replace the battery with some tools
Modes: Moonlight-Low-High-(Turbo?)
Brightness: Moonlight = 1LM, Low = 15LM, High = 100LM, (Turbo = 360LM ?)
Price: below $10
Other:
I know that the goal is to limit it to roughly 40mm x 14mm and ~12g, but… maybe it would be better to make it a little bigger (2x10440?) and put there a nice driver to be able to claim it the longest running double AAA on the market?
Acebeam UC15 Keylight (uses 2 x 10440 or 2 x AAA)
I would suggest to put second led like Nitecore did in their Tip2
Other shapes for inspiration (size could be corrected to contain 2x10440):
Nitecore TINI or Mateminco CSF02 “AKA” Astrolux K1
MecArmy SGN5 or YLP Scorpion X8
or Frelux Synergy 1
phouton - The light won’t take a charge anymore. When I charge it the blue light comes on but the red low battery indicator never shuts off (low battery indicator comes on at 2.6 volts). To Rovyvon’s credit, I contacted them and they are sending a replacement under warranty.
that is a 2x aaa light with Lumintop Tool/IYP electronics… Way too big to be on a keychain
meanwhile you can get a stainless 10180 light for under $20
speaking of deals, some of us are buying Copper Tools for $10
Side switch allows for accidental activation.
2 batteries makes it too big for a keychain light.
15LM on low is too low for any practical use.
With the specs on the second post, I’d buy one or two.
High cri 4000K sounds good to me. I’ve got two other lights with this emitter and I like them quite a lot.
I haven’t read the entire thread but for the charging port, I’d prefer it to be under the threads of the head instead of covered by a rubber gasket.
Heres an eventual contribution to this thread!
Disclaimer: a) I don’t use this light as keychain; b) I use a Rovyvon light as keychain and as a neck light and…they will be hard to beat for me! Still, I am open to this thread’s development!
This is the DQG Slim Ti in it short format. It takes a 14250 (half size of an AA/14500 cell) and 1 or 2 AA / 1x 14500 batteries when using extension tube(s), has 3 modes, no memory, XP-G2 on the rosy side and a TIR (originally was narrow beam, I modded and put a pebbled TIR).
Compact, bigger duration than an 10880, just probably larger.
Driver and LED come together, switch is replaceable, doesn’t have integrated charging, batteries are replaceable too!
Review Thread: “REVIEW”: DQG Slim Ti (1/2 AA and other batteries) ***[DISCOUNT CODE ADDED - 05/22/2018]***
Later I can compare it with some other keychain lights in terms of size and output (using an AA cell, as I don’t have any 14250, yet)!
I can tell that it is smaller in length than a RovyVon Aurora A8U…
Very interested and like Noir’s specs on post 68.