Sometimes part of learning is failing, although I try to avoid that part if possible! 
Oh I’m well aware of that. Like you, I just hate failing.
Parts kit coming at mtn?
Is there interest? You're the first one who's asked for one. If there's a few more I'll put one up.
Oh… I just assumed. I don’t plan on making enough of these to make a larger order from mouser worth it. How many parts will be shared between this one and the 20mm?
Preliminarily it is all the same except for the flyback diode and sense resistor, although maybe I’ll end up with two different 20mm boards so that those who have parts for the 17mm and don’t need more than 3.5A-4A can use the same parts.
I’m actually interested in complete driver, do you offer them now or in the near future?
I probably won't be offering them complete for a while because I just don't have time to build them right now. I have built a few for a customer who asked about them a few months ago, but besides that I've only built them for myself.
That said, I have two of them complete right now that I've built that are just sitting on the shelf I could sell. I will list them on the garage sale page.
I will get a parts kit up tomorrow.
Richard, do you already have enough spares for a parts kit now or would you have to order? Reason I ask is I already have a order with you that I’m sure you haven’t had time to complete. If you already have the stuff then I’d like to purchase a couple kits and have it shipped with the other order. If you would have to order it, I’d probably just place another order with mouser. I can always find more stuff to buy I don’t really need, just like shipping with you! I have a 2S UF-1405 that I had planned on putting an E2 Torch in and using a low current buck, but I’d rather push a G2 at 4a.
The Mouser parts list is putting me off a little. DigiKey I've found cheaper in the past when comparing qty 1 or 10 for example, so I've only ordered parts from DigiKey up til now. Also trying to figure qty of boards to make in this size, what lights best fit, etc. I'd probably want to use it in 1 or 2 e-switch lights, or lights with a wider driver, so, bigger board options (and higher power) of your next generation may be better for me, or take the chance with a contact board setup which you are not recommending. Dunno yet.
I shop at Mouser based on price, and price alone. For me Mouser has almost always been cheaper than Digikey.
For e-switch, you've either got to be OK with some quiescent current drain, or go to a bigger driver layout with more parts.
Hold out a little longer for the bigger boards. You have to think of the thermal path of one of these like you do with a high-powered LED---it will fry itself if pushed hard without a sufficient thermal path. We are pushing it already by making everything so small.
Hhmm - I gotta re-check part prices again then. Maybe I was just spot checking the MCU's, FET's, diodes - Hhmm: I see the ATTiny13A's are definitely cheaper at Mouser....
Yep, can't think of much I can do with a buck driver at 17mm. I have no P60 tube extensions, but think I got 1 or 2 for Convoy C8's, and pretty much all my 2S cell lights use a bigger driver. The limited 18350 capacity can't justify converting a 1 cell 18650 light over. Also 4A is very limited if driving 2S cell triple LED lights, and converting the 3 LED's to parallel - obviously 2S cells driving 3S LED's won't work with a buck driver - boost is needed.
RMM,
One group that may be very interested in this driver is laser enthusiasts. Especially, if it provides pretty clean power. Most laser diodes need much less then 4amps of power and some have fairly high Vf's. They are always in search of a good boost and buck drivers. If you don't belong to Laser Pointer Forums, there are some senior LPF members here on BLF. Maybe one of them can help introduce you there to get you some street cred.
EDIT: Edits made to add content.
I've looked at a few drivers over there before. I think they'll be surprised to see that none of the IC markings have been sanded off and the files and information are available for free.
Well I am certainly impressed. I'd probly have use for a pile once we can buy em at Mtn. :)
What does "HP" stand for? High Performance. 
I've got one running at 5.5A in a UF-1405 right now and it seems to be holding up well so far. I ran it on 100% for 7 minutes straight and it didn't burn up, so I think there's a good chance that it will hold up in the long run. That light finally runs like it should have from the beginning. A bit more testing is needed, but I think that is the direction I'm going now. The same design will be able to be used from 1A all the way up to 5.5A in 17mm by just changing a few components on the board.
Also, I was able to build and test a 20mm. It will be available soon. That one can also do 5.5A (or maybe even more...haven't tried it yet. The only place I'd want more would be in powering a triple or MT-G2. For an XM-L2 5.5A is sufficient).
Hehe it looks like you are going to make me regret ordering a 1504 instead of the 1405 
Good job 
Did it hold a steady output at 5.5A like it did for the 3A version?
I hadn’t considered that very nice characteristic of the buck drivers before.
I ordered the 1405 instead of 1504, just for this! Is the HP version on the same pcb with different components? or different altogether?
Different PCB, but only slightly different. Two diodes instead of one with an extra input capacitor pad.
Also, you need a Coilcraft inductor for this one, and it needs to be in a host with a pill design that is big enough and beefy enough to carry the heat away from the driver. I wouldn't stick this one in a P60 or something small.
We are really pushing it thermally with these tiny components. I have only run this 5.5A through a single set of 26650s so far, so it really needs more testing. I would hate to have them all start failing at the two hour mark. The regular ones have seen 30+ hours at 3.5A and 4A inside of an actual flashlight, so I know that they can work.
I've thought about unmasking a bit more of the copper on the thicker heat carrying traces so that they can be loaded with solder to reduce thermal and electrical resistance. Every little bit can help here. A 4 layer board, and a board with thicker copper would also provide thermal advantages if set up correctly, but those add to the cost significantly. Adding an optional bit of solder does not, so I am going to do a few tests to see if critical component temperatures change significantly with solder loaded copper planes.
Yes it does.