While I was resoldering, I didn’t solder the wires as flush to the mcpcb. While screwing the bezel down, it was enough for the bezel to touch the solder from the positive wire. This caused a short and the light started flickering. Fortunately, I had a protected cell.
What are some safety hazards for the new and experienced modders should be cognizant of? This includes safety of tools, environmental etc (inhaling solder smoke etc etc)
I know you asked about “safety” hazards, but I ended up thinking about all of my modding screwups I can remember.
For personal dangers:
For the equipment dangers:
I really liked bullet point one. I did actually burn my forearm with the soldering iron, the flashlight was unstable and I tried to grab it so it wouldn’t fall. Well, as I tried to grab it, the soldering iron rested on my arm and burned the shit out of me. I have about a 1 inch long white indentation and red around it. Burned skin smells bad.
I’ll add:
I’m sure there’s so much more that I’ve learned the hard way while modding, but that’s a good start!
One suggestion: When you order parts for modding always order spares.
Nothing like having a fun night of modding planned, messing up, and then realizing you have to put the whole thing on hold for another 6 weeks while you wait for replacement parts to arrive.
The greatest danger to modding is making a light so good you have no need to buy more lights.
Having a growing accumulation of drivers and other parts that you bought for a good reason you no longer find interesting and can’t identify well enough to give away.
Oh yeah, guilty of this myself. I never order just one of any modding parts anymore. By the time the replacements get here, I forget what it was I was planning on doing and usually have just moved on to the next mod. Certain things I buy more than enough just encase I need them modding something else, then I can mod the light right then instead of waiting 3 weeks. It feels like I’m running a auto parts store where you have to keep the most popular parts in stock instead of everything being a special order.
A great danger of modding is that over time you buy a lot of expensive equipment for that, in my case surpassing the combined value of my flashlights. Money that of course should have been spent on flashlights. 
Addiction.
In case something has broken down: there is nothing wrong with rebuilding it better than it was ever before.
In all other cases: if it works, don’t fix it. 
It can get highly addictive. With a financial collateral damage that exceeds the worth of the benefits.
If you choose to disobey these laws of nature: always wear protection. Like (safety) glasses.
And, as mentioned before, I have accumulated a huge load of equipment I barely use except for modding every other month. Approximate number of drivers: 21 - all unused and/or not working.
Literally 50 bags with parts that came through the years. hundreds of resistors, capacitors, cables, wires, optics, and even unused hosts.
The way I managed my mods was very wasteful and I hope to remedy that somehow. Also lost my interest in modding lights or even collecting them. After you have done all the mods you wanted to do, what else is out there? I have 600$ in unused lights in boxes (good lights, but most of them not “modern” lights; solarforce, older skyray kings, lots of convoys and thorfire)
Never had solder “jump”, isn’t it the flux at a too high temperature?
As for the dangers not related to tool use… i think the main one is making a short with the reflector. sometimes even with a centering ring the joints are too fast and touch the reflector.
I would say, damaging a flashlight
Yesterday I was attempting at modding my Olight S1R Baton I with a LED swap and ended up damaging something, as now the Moonlight mode doesn’t work properly. Other lights, drivers, leds and switches have been damaged along the way.
BUT, as some have already mentioned, spending money and getting addicted is the worse evil you’ll find existing when you have been bitten the “modding” vampire 
I don’t know how it happened, maybe someone else can pitch in. The LED wire came off of the solder joint on a copper dtp board while soldering and I heard a “pop” sound before very hot solder splatter was all over my face. Just happy I wore goggles.
Because the parts are so small, our faces are very close to the soldering action.
With age come (a few) advantages. I have to use a desk light with a 4” magnifying glass 
So my eyes are well protected. And the rest…… Does not matter any more. Did I say age?
So true, and parts are relatively cheap. This is a hidden safety hazard as you’ll likely punch a wall for having to wait
Haha, I have a rule when using a soldering iron or a knife, that I don't do anything else while I'm holding the iron or knife. For the iron, that means if I drop something, I put the iron in its stand before I grab what I dropped. For a knife, that means I fold it or put it somewhere safe (for example, not somewhere it will be bumped off and fall on my foot) if it's not a folding knife.
I know I would burn myself or something else important if I got distracted while holding the iron.
Modding opens the potential of:
-my flashlight burning my pockets
-people who used my light will drop my light due to it being too hot.
-people leave my hot lights on because they didn’t know / too scared to hold a hot light
-inviting more people to turn on the light while pointing at themselves to test power (I still don’t get why people try that every single time)
For personal danger, I couldn’t think of any other than shorting the battery due to my incorrect installation/solder
Usually the dangers are affecting people who used my lights irresponsibly
For me, as has already been said by others;
Same with guns, ammo, knives, & fishing equipment.
