Let the caller choose the random number generator.

[elementh]

Functions and methods that use random numbers should probably have a signature like fn pick_brightness<R: Rng>(&self, rng: &mut R, ...) and then it should call rng.gen_range.

It should provide convenience methods that use some default so specifying a Rng doesn't becomes mandatory.

[nms-scribe]

I was looking for this capability, the issue says it's completed, but I don't see this in the API. Would it be possible to revisit this and add this as a feature?

[daxpedda]

SmallRng is not portable, which won't make it work in e.g. multiplayer scenarios.
But more importantly, it can't be "saved & loaded", because SmallRng doesn't support retrieving the seed or Serde.