Yup! Done that, I posted to What Did You Mod Today, though I’m not quite sure it counts as a mod!
Not sure if this works:
I really like the blue GITD and the blue anodising on the switch retaining ring. Took a few goes to get the tape in perfectly.
The blue GITD tape charges better with higher CCT light, this photo is roughly what I see with my eyes immediately after switching the light off, in daylight conditions. To stage this photo, I shone a LW UV lamp at the TIR!
Is that a M21H with a different bezel?
Yep! Simon sells a crenelated bezel that fits it.
I wish the M21E had a smooth bezel available for purchase.
(I don’t like crenelated bezels.) 
How similar to the M21H is it? If it’s the same size and threads, you can have mine
Thanks, but it’s the wrong size. 
Dang that would be neat! I recall one stop throw shop having a flat light with the catadioptric you linked, many years ago. I do think a box version of the GT would be a more practical design.
I do like how generalizable the idea is behind the cheap TIR I linked: a super shallow TIR to reflect sideways-emitted light, and a convex lens to collect all of the frontal emission. Also takes care of tint shift issues. Current reflectors/TIRs take up way too much space in large throwers, and so do Fresnel lenses due to the focal length. A catadioptric or convex-TIR combination would be a great solution.
I assume you’re thinking of the Eye of Sekhmet by silent thunder ordinance?
It is a very unique light and I’m disappointed the optic hasn’t been used in other lights.
I’m not sure what the throw would be like on the AliExpress optic… I’ve a project light I’ve been meaning to finish for years, might grab one of those lenses on the off chance I can make it fit- the bezel diameter is about 125mm though so I’d need a spacer or something.
Edit: I see this seller also has this big chunk of plastic:
https://www.aliexpress.com/item/4000223404801.html
93.9mm diameter, 54.2mm height!
Whoops I misremembered–yes, that’s exactly the light I’m thinking of! With a modern throwy emitter it should do well over a kilometer.
I am very curious how well the Aliexpress optic works, the 80mm one is a bit suspicious as the surface appears to be frosted, but there are slightly smaller clear ones. Though they would be a waste of your 125mm diameter host (what light is it?), and the only optic I can think of with that diameter is a Fresnel lens, which has its issues.
Aaaaaww…
This is a bummer, man!
The biggest TIR light I have right now is the Acebeam L19.2 with its 55mm head. That optic is a piece of art. Unfortunately I didn’t take pictures when I was disassembling it but it’s very deep, a lot deeper than other TIRs I saw on the market.
Wurkkos TD01C if you want a thrower.
Unfortunately the efficiency of that light (along with output and throw) is pretty abysmal for its size and price.
Yes, it doesn’t deliver claimed lumens on turbo, but I am more interested in sustained output rather than short time high output. It is efficient, buck driver, throw and beam pattern is excellent. What not to like for $33 shipped? (no battery)
Can’t find any references to it now, but I bought a portable lamp off eBay in about 2016, it’s an ex-navy “damage control lamp”, originally ran on a BA15s halogen bulb and lead acid battery. It’s got a fairly shallow reflector housed in a tiltable aluminium head, mounted on a ~10" cube battery box.
The whole thing is powder coated in battleship grey, and the only mount on the inside of the head are two tiny screws to fix the bulb holder in place, my biggest headache is finding something that will have good thermals for mounting an LED. I’ve got some sheets of aluminium I plan to cut into disks and thermal epoxy together, rather than trying to hand carve a big block of aluminium. It’s an ongoing project 
I’ve also found large optics (60mm) from LedLink, a company I’ve never heard of before.
I didn’t vote. My main flashlights are headlamps for moving fast (trail/orienteering running, skiing, mountain biking), so I have to say multiple elements with different focal lengths running all at once. You’ll see these in orienteering and bike lights. So at least two elements, like a wide and narrow TIR (Lucifer M6+ headlamp for example) or a narrow TIR combined with a white reflectorish backed mule for the diffuser (LEDX Snok for example). Then you have orienteering headlamps with 4 to 9 TIRs or diffusers or reflectors running all at once. It’s exactly the idea of a rally car running a night stage with different types of driving lights covering the entire field of view. The idea is to get a smooth, evenly lit carpet of light on the ground wide in front of you and going smoothly off into the distance.
Somewhat the same idea, there are also the engineered optics like car headlights that aim to get a specific field of view with or without a cut off. Bike light maker Outbound does this because it was started by a car light optics engineer. Outbound has done single large optical elements, as well as what looks like one-piece combination of TIR elements.
LEDX Snok
Lucifer L+
LEDX Cobra
Outbound Trail Evo
The medium modes are 30% less efficient than L21B, and maximum sustainable output is 25% less, so even in sustained output it is quite poor. See full discussion here. The most likely cause of the inefficiency is a poorly-designed buck driver than performs worse than a linear, or a TIR that is extremely lossy.
That sounds like such a fun project, you should enter it for the OL competition!
I realized that both the LedLink optics and the Aliexpress ones state that they are designed for COB emitters, which might make them too imprecise to correctly focus throwier emitters. The LedLink, for example, has a orange-peel like texture, and who knows about the Aliexpress ones. The Carclo would probably out-throw everything else with the same diameter, except that it’s not available in >60mm. What LED are you thinking about using?
Frankly speaking I didn’t get the comparison with L21B as I wasn’t comparing it with anything. And I am sure I can name a few models that would output more than L21B and be more efficient than L21B at 30%, but what’s the point? Also efficiency will always be less on TIR lens compared with reflector which L21B is.
