I too would like to see how they are made. I would assume that the layout would be on a drum and then most of the design and cure would happen in a mold. Having molds built and for every type of track (length, width, paddle design, etc.) would be very expensive.
As a side note I've been thru a Michelin giant tire plant and got to watch the process on what it takes to build a tire. I would have never guessed that all tires start out being built flat on a drum. Once all of the casing material is placed it is then turned into a crude shape of a tire thru methods of the durm it was built on changing shapes and air filled bladders. After it's somewhat of the shape of a tire the tread material is applied and then off to a mold. Once in the mold a hot water bladder is inflated inside of the tire forcing equal pressure all the way around and in turn forces the new rubber into the mold shape which is the the unique tread design of that mold.
