Well strictly sneaking for diodes I had an idea, with flash cavities, it would just be getting them close enough together.
So I think op posted something about a cylinder, well what if a coated cylinder was used, maybe shooting....ah new idea. Screw focusing all the diodes, why not make a holder for all the diodes, decanned and just raw light spraying into the cavity, and then focused down. Then its essentially a multimode multi diode cavity.
Maybe that's what was done with that two diode host that puts out like 3W?