Post reserved for the moment. This build would be a modification of a Convoy S2+ into a mule running Seoul SunLike emitters, which are violet-pumped LEDs with higher CRI than any current blue-pumped LED available.
The objective is to complete the build with the cheapest components and most elementary tools, thereby demonstrating that a violet-pumped ultra-high CRI light is easily accessible to almost any modder.
All the components I got for this mod!
To the left are Seoul SunLike 3030 LEDs in the 3V, 5700K variant, which are the objective of this mod. The large reel in the middle are 3V 2835 emitters in 5000K–the soldering footprint is essentially the same, and they are cheap enough for first experimentation.
The paper reel on the right are R050 resistors, for the purpose of swapping into a Convoy 5A linear driver. The original driver has a R020 resistor, and swapping these in should reduce the current from 5A to 2A, to not overdrive these emitters too much. The resistor footprint is 3216 in metric units, 1206 in imperial.
Down there is a PCB I intended to flow the SunLike emitters onto. It comes with 6 2835 emitters stock, and I figured that I could scratch off the solder mask and flow more than 6 emitters onto the same PCB. Thanks to u/crbnfbr for assuring me that this is feasible! The 24mm is too big to fit into a S2+, and I figured that sanding the edges might reduce it to 20 or so mm without losing too much of the outer trace.
The combined cost of the 5700K SunLike (20x), the pack of resistors (50x), and PCBs (10x), came out to $7.6 without tax, around $8.3 with tax and shipped. I got them with another order during an aliexpress sale, so shipping was free. Therefore, with an existing S2+ triple with 5A linear driver, and access to basic tools, under $10 is required to perform this mod.
Onto modifying the PCB. I first removed everything from the board (candle for the reflow!) to get a better look at the layout and emitter footprint.
I got this board because it was advertised as 5V, which suggests that the LEDs are wired in parallel, which turned out to be the case. In the left image, the + pad runs along the outer circle of trace, passes through the 3 resistors on the top, and then comes back in. I intend to reflow some LEDs onto the resistor pads, so I would need to eventually connect the existing + and - pads, and then open up a new + pad somewhere on the outer circle.
In the right image, the board has been sanded to a shape that fits inside the S2+. The sanding is asymmetric because I wanted to preserve the positive trace connection, which runs just to the outside of the mounting holes. The board to the right is actually not the same as the board to the left–it’s a redo because I disconnected the positive trace in the first attempt and could not find a nice way to reconnect.
I also scratched off some mask to reveal fresh copper traces to cram more LEDs onto! Then I opened up a + pad just below the bottom-right mounting hole.
Worth noting is the fact that there is quite a lot of separation between the inner and outer traces, which means an LED soldered on top would not be in direct contact with much of the trace area. This presents an issue with heat dissipation, but hopefully with enough emitters and a low drive current, the suboptimal heat path would be ok.
Up next: how many SunLike LEDs can we cram onto these newly-exposes traces?
I originally reflowed these 2835s onto the board, but replacing them with the 3030s, which have better power handling, was no trouble at all. I’ve added a bridge and another piece of wire (red) to move the positive contact to the center, where it can be soldered to the driver wires. Time to put them into the light…
It lights up! There are still issues to deal with, though: there is no optic compatible with this setup, which makes it difficult to get a usable beam (many petals due to the multiple emitter setup) and to keep the glass front lens fixed. I decided to build a central pillar of sorts to press down on the PCB and support the glass lens, more later. Please excuse the gross soldering job, it won’t be visible for long!
First of all, my apologies for leaving the solder joints out in full view for so long!
The good news is that they are now covered in the actual light. I’ve built a pillar of sorts using UV resin to go between the PCB and the glass lens, applying pressure to both components. The bottom of the pillar was cut to fit the wires, and the lateral surface was painted with a “purple” (really royal blue) glow powder, which can only be activated by violet or UV light.
The light does activate the glow without issue, which is further confirmation (aside from a spectroscope view) that these emitters are indeed violet-pumped.
For diffusion, I simply covered the glass lens with frosted tape. There are still asymmetric artifacts in the beam, but they do not come across on camera; they are also not noticeable IRL as long as the light source is not moving.
And used some fluorescent pigment plus UV resin to phosphor-convert the blue tail switch light to white:
Funny! 
The royal blue glow looks good. Nice job.
