Of course it’s possible. Depending on what exactly you mean, it could even be easy. CRX made a rotary flashlight by hand from scratch.
Something with an interface like the Jetbeam RRT-01 (and other related flashlights) would be pretty difficult. Do I think it’s beyond the collective ability of BLF’s members? Absolutely not. Would it happen? It’s unlikely. It’s a pretty challenging task, especially to do well. And to be worth doing, it would have to be better than RRT-01. More power? Smaller? Better heat handling? Something. And we’d have to try to maintain water resistance and hope there’s no patents we’re unaware of.