@vaartis Trail renderer isn't too bad either, though I wouldn't recommend it, as it is a bit too simple.
Still, are you on some ancient version of Unity or something?
Anyway, when it comes to trail, if you want something nicer looking, and more customizable, the way to go is particle system.
Set the emitter to emit only on distance, and there you go.
@vaartis There's also the Visual Effect component that is similar to a particle system, but runs on the GPU (if memory serves).
I don't have much hands-on experience with it though.
And good luck with whatever you're making.