I can't find the thread where the "Rails!" level was uploaded, so I'll start a new one
I think this level was made by seanarmadillo.
Some background before I get to the point: my 3 year old son likes to watch "the ball", i.e. he wants me to start spectator levels in AR, with the view set to tracking. So I downloaded quite a lot of them from the forum and watched them with him.
What's my point then? It's that "Rails!" is the best of them all. My son likes it because it's long and the armadillo travels in a little cart . For me it is it's beauty and the clever solutions. I especially admire the way one of the carts first has it's elastics over it, then under it and then over it again.
I salute you, seanarmadillo!