YouTuber James Risner likes trains big and small. In the videos below, he set up a spiral track and ran a long series of HO scale model trains along it. In HO scale, the ratio of model:real train is 1:87.1.
The sound in this is a little grating. I suggest turning it down a bit, and watching the locomotive in the front (or pick one of the other locomotives, and just follow it around). It's utterly mesmerizing:
And here's a similar concept, but the trains never leave their spiral track (!). Again, pick out a locomotive, and prepare for some light self-hypnosis.
And if you liked that, here's a quadruple double helix, apparently set up in Risner's living room (I love the stacks of CDs holding the thing up!):
Are you relaxed yet?