Projects like this are a great demonstration of just how far hobby projects can go today by exploiting some fairly recent innovations. In particular, designing a custom lens geometry and having JLC manufacture small runs cheaply is especially impressive; and of course, what you can get out of a modern LED is just absurd.
I agree, thanks for underlying that point. I did not intend to write an ad for JLCPCB, but honestly I kinda did. I feel like it's deserved praise because the service is really great. Low volume custom PCBs with assembly service and 5 axis CNC with a minimum order quantity of 1 is game changer for prototyping. Combined with a software first approach to design with tools like build123d, the flexibility of 3D printing and 5 axis CNC, and the addictiveness of the high dopamine feedback loop of software dev starts to bleed over to hardware dev. Shipping delay is the last hurdle.
About the lenses, I did consider injection molding during design, and one supplier even quoted me for $20,000. So yeah, very glad for JLC!