Similar to the ZXSC380 that was mentioned, the ZXLD381 is cheap and easy to implement. While not designed for a 5mm LED specifically, there’s no reason why you couldn’t solder one to the pads on this driver board. I have some testing details about that here. Heck, I think I still have some of these boards and components sitting around. If so, they wouldn’t take much time at all to build some up. And as simple as a design as this is, I could throw together a new driver that’s meant for a 5mm LED and a AA battery.
As far as some good 5mm LEDs go, you could try and find some Yuji’s or see if any of these are available.
BTW, neat concept with the 3D printed twist housing!