I'd wager they're pretty good. If you can leverage a parabolic reflector at a light's focal length, you can get them to collimate in a way that approximates the

I'd wager they're pretty good. If you can leverage a parabolic reflector at a light's focal length, you can get them to collimate in a way that approximates the sun by appearing to be pinned near-infinitely far away. The reflector is generally what takes up the space, but it's necessary(ish) -- you could approximate the effect by using a fresnel lens at the light's focal length, but it yields a smaller light with rainbowing effects. [This video](https://www.youtube.com/watch?v=6bqBsHSwPgw&t=843s https://www.youtube.com/watch?v=6bqBsHSwPgw&t=843s) does a good job of showing how to make your own, as well as illustrating how good the effect is, while also demonstrating why space-hog implementations are likely to yield good results and slimmer ones not.