Yes, you need proper eye and full body skin protection. I won’t advice you on what is proper (I was never interesting in using UV-C myself) but stress that UV-C is highly harmful.
Just to do it, show off to strangers on the internet or friends. I’d try to build an x-ray flashlight if it was financially feasible, tho I see LEDs seem to bottom out well before x-ray territory. Probably different tech altogether and not a flashlight type of device.
EDIT: There are DIY x-ray machine builds available. Not a flashlight at all, but still feasible if you have some extra cash, time, and no concern for personal safety.
About the feasibility of UVC flashlights?
Why does a 21700 battery exist when a slightly shorter 21650 would fit into existing chargers?
Good question!
Tesla and Panasonic thought it was a good size for their use. That was after using 18650s as other car makers did for many years. And now they’re moving on to the 4680. So yes nothing to do with flashlights or chargers.
The 4680 looks large but maybe it could be an alternative to 4x18650 or 8x18650 torches/flashlights.
If I ran out of Attiny25 MCUs is it possible to use Bistro with clicky tailcap switch on an Attiny85?
Why do people chew applesauce?
slmjim
It’s absolutely possible. You can’t go the other direction with some firmwares because the 13 and 25 have less flash than the 85 so for example anduril doesn’t fit.
I’m not sure what, if anything, you’d need to change, but I’m sure it can be done rather easily.
I don’t get it. That’s a whole i1R or whatever in there, no?
That flashlight should charge.
Your charger must be broken. 
It’s not gonna charge. The light’s backwards. The pointy end goes down, and the flat end against the slider.
It’s an Olight, that’s why it isn’t working
Thank you Scallywag. I will just try if it works.
The Convoy SS bezel fits on the Sofirn C8F. These lighted switches will not fit as the switch PCB on the C8F is 23mm. I made a picture of the switch assembly in my review here: REVIEW: Sofirn C8F 21700 (comparison, beamshots, teardown PIC HEAVY)[21700, 3x XP-L HD, C8 format]
The Sw45k leds will have a nice tint but maybe only an estimated 1500-2000 lumens.
Recently I mounted three 6V 90CRI XHP50.2 with the Convoy M21C-U boost driver. Looks and works nicely. I will also put some Luxeon MZ leds in another C8F and see if I get a donut hole in the beam. However, these mods involve a bit of work.
I would not recommend XPL2 leds in the C8F because of the tint shift. The LH351D leds should be nice, they are quite rosy when dedomed.
I will post some pictures in the ‘What did you mod today?’ thread. EDIT: Pictures I used three 16mm MCPCBs. They are not ideal as I needed to cut them smaller and the leds are difficult to center. The only shop that has a 5050 MCPCB for the C8F is Cutter but they have expensive shipping to Europe. I also filed the driver a little to fit. The retaing ring needed some filing as well to not touch the outer parts on the driver.
I also thought about the EC03 for this build but you will need a copper ring or a bigger board to adapt the 22mm driver to the bigger size.
If you would slice the LH351D the 5000K are better. They give around 4200K and a rosy tint. The 4000K LH351D tent to be green. Slicing is not difficult with the right spacer. There are no bond wires on the LH351D, just don’t slice too low or the led will turn blue. I once accidentally hot dedomed a led but it was messy and exposed part of the blue die.
Just wanted to follow up on the story. Hank usually responds to emails the same day. He asked if I could reflash the driver. I didn’t have the equipment or the know-how so he said he’d send a new head. That arrived just under a month ago, just before I went on a trip. In the meantime I tried scraping off the burned material. I tried to scrape off as little as I could but I scraped too far on the most burned LED. Blue light was emitting from a small area which I could not dismiss as just a change in colour temperature. I would have been better off leaving the LEDs as is. But maybe the experience gained was worth it as the replacement head did arrive after all.
I haven’t used my resurrected D4v2 a huge amount (less than 90 minutes) as it’s not the only torch in my collection and it is still summer. But it has decent lumens and the E21A LEDs make it compelling to use for the tint snobbery alone. However I am still afraid to use turbo mode after what happened last time. I did notice the replacement head had a board of a different colour (see below). At least we can confirm the regular D4v2 board WILL burn the phosphor of E21As very quickly. As Hank sent a whole head I have a spare regular bezel and clear optic. A bit of a different Emisar experience to what I expected but Hank was willing to offer customer service and replace defective product.
Replacement (white) board versus the original (red) one.
Should I be worried about storing lights with their magnetic tails close to other lights drivers 
It appears you have received the direct driver before with the E21A and that is why the LEDs burned, those 4pcs E21 cannot take direct drive.
This new driver should have the linear FET only working and have the direct drive FET disabled.