I’ve started to build up a small collection of tools to help with modifying flashlights:
Opening tools:
Strap wrench for tubes and bezels
Circlip pliers for bezels and tail caps
Camera Lens Spanner Wrench (is that the name?) for unscrewing pills
Hemostat forceps for gripping small tubes
Emitter swap tools:
Tweezers for moving wires and LEDs
Soldering iron
LED dedoming/cutting:
Feather blade
Are there tools that you’ve found particularly helpful for certain modding tasks?
That’s a nice set of tools! A lot nicer than the ones I’ve been accumulating from no-name overseas sellers…
You’ve probably already got something for this, but I’ve found a hair dryer invaluable for tackling flashlights with glued heads/pills.
My wife seems to be happier now that I’m using a heat gun from a local hardware shop instead of her hair dryer going missing. 
I accidentally melted the lens in a C01S while trying to soften the red loctite. 
Hemostats worked well on an orange C01S. I guess there was less glue.
I’ll get a “UYUE 300W 100m * 100mm LED Preheating Platform” next to try to make it easier to reflow emitters.
Calipers
Vise
I use a lot earbuds with etanol for cleaning, wooden toothpicks for spreading the grease/paste and ticking the led during reflowing and hobby knife for various applications.
Right, and thermal paste - to replace all the stuff you clean off when you remove the emitter board.
Otherwise the new LED you put in may die a lot sooner than you expect!
Every light that comes in gets a thorough physical. Total disassembly except the soldering.
Looking for burrs, loose pieces of metal, damaged leads, and mis-aligned O-rings…
Clean everything (first dry, then with alcohol), new grease, new thermal paste (if looks iffy).
For unscrewing bezels I use, what’s on the other forrum called, the Teva method.
Works like a charm, if a bezelring is sticking out from the bezel, and is not glued.
Press the bezel tight against the (clean) thick rubbery soles of your trekking shoes, and turn.
q-tips?
thanks for the photo of an open C01S head…
how do you use hemostats to open the head?
I recently tested using my hotplate at 100C to soften glue in a light. It worked on one, not so well on another. I need to refine my technique, possibly use a higher temperature, and or a few more minutes to let the head sit on the hotplate and heat up.
My strap wrenches are worthless, they just slip and spin
So I use vise grips:
Here is a tool I could not do without, a Jewelers Visor:
I have had some luck with using a heavy plastic bag in a pot of boiling water.
I used hemostats on the threads and my fingers on the C01S head. Damaged threads slightly but no impact to performance.
I have a blue C01S and a red C01R.
Managed to open both of them with my bare hands.
C01R just to look. Blue C01S to swap the white led with a blue SST20.
*Can anyone test or say !!!
*Said it a 100 times ...flux .flux .flux ..OK now 103 times :)
I use my beat up micro shears to tighten and loosen heads and tails .So I'll include a couple pairs of cheap micro shears as must have items as well as a set of small files and a dental pick .
I started with the Panavise model 201 like you have and it does a fine job but then I borrowed a Panavise model 381 from a friend and was utterly amazed at how well it worked.
Bought a 381 the very next day.
I highly recommend it. The vacuum base on the 381 is a joy to use.