I found out a few days ago that my neighbors updated their website......
http://www.protocam.com <---check out their mobius gear
They have been in the business much longer than I have (since 94) and they do high end prototyping.
The easy answer to making this model is to use an additive manufacturing process such as a 3d printer.
One rather interesting way to make this would be to find a really long "rack" (I'm referring to the rack in rack&pinion gears).
Take this "rack" and twist/bend it 180 degrees and connect the two ends.
You would still have to do many calculations to figure out the size needed for the pinion and center gears.