I work in aircraft inspection. I have bought a few expensive flashlights in the past and have even assembled a few from parts to get what I wanted. My last good light light was a diy 2 X 26650 cheap host with the domed zoom-able lens, a 3 amp driver and a single XML2 U2. The cheap zoom dome hosts do to very good job at providing a very even flood up close. 99% of aircraft inspection work is done at arms length so a very smooth up close flood is important. Other features such as an easy to use driver and battery life that’s decent are also important. Being able to swap out batteries is also important to always have a fresh light at the ready. The 1200 lumen of my previous light was adequate but a little more wouldn’t be bad. Too much more would likely be too bright for close up work. I’m looking for recommendations on complete flashlights as well as parts that I could use to make one if it works out better. Thanks in advance. Brad
I’d look at the Sofirn IF25a in the 4K version. It’s a SMALL light that packs a 21700 battery. I run a 5000mAh/10A battery (50g) in mine and its PLENTY of light for anything outdoors out to 150 yards or so while giving you max run times.
But best of all IMHO, is the wider beam compared to a lot of similar sized lights. I also use mine for up close work and the flood and spill are nice. For close up work without a lot of output, it ALSO won’t heat up like it DOES on turbo mode. You’ll get long run times, plenty of output and the 4k version will render better color compared to the typical 6.5k lights sold on raw lumen output Vs. quality rendering.
The Sofirn SP40 headlamp with magnetic tail cap is also a cool little light using the 18350 tube (included) if you’re in a tighter spot AND need a smaller form factor. IF u need a headlamp, it’s also a great tool there too of course. 
To make a noticeable difference from 1200lm you’d need at least 2000lm or more. A jump to 1500lm or so would be hardly noticeable.
Something like a C8F-21700 with diffusion film would give a nice blanket of bright light, and a second 21700 would give lots of oomf.
Sticky diffusion film could be cut to fit, peel off the backing, and slap it right onto the front of the (spotlessly cleaned) glass. If nonsticky, you’d have to remove the bezel and thus front glass, and sandwich the film between glass and reflector.
The op say 99% of his work are at arms length, so I took some photos of the FW3Cu and the mule Amutorch AT40 (both use 18650) just to show how floody a mule light is at the same distance, arms-length, compared to 3-led FW3Cu:
The Lumintop FW3A on the left…
Convoy S2 with 60 degree TIR optic?
Are you real sure you had 1200 lumens? At an arm’s length away how wide do you really want the beam to be? Almost anything other than a zumi is going to do better.
The new Convoy Z1 zoomable might be another consideration if you really need a wide FOV up close. But as LB said- diffusion film works great when done right (and agree the C8F would be another super light).
BUT… If I need to get into tighter corners I’d do one of the smaller 21700 lights (like the IF25a which is 1 3/4” shorter than the C8F with a smaller head also).
My arm’s length measured at 26” away from a white wall just now gave me a 9-10” wide beam with very nice diffusion in the spill using the IF25a. The C8F just gave me a 4” beam with more light in the center and a “tighter” over-all beam. So almost 3 times more light which is nice and even with the IF25a (up close) Vs the C8F. But diffusion can be used on any light and might be a good option if you don’t want a zoomie.
Good luck!
The Convoy Z1 looks like an excellent candidate. The zoom lens up close always seems to have excellent flood and on occasion we need something farther away. I am a big fan of the zoom lens. The SST40 LED in this light seems like a small upgrade over the XML2. Regarding efficiency would another LED provide the same lumen at a lower wattage. Zoom hosts are dirt cheap and I wouldn’t mind assembling something.