Simulating the Thomas Inch Dumbbell
While it would be nice to own the original Thomas Inch Dumbbell, or at least a copy, they are costly. It is also not possible to change the weight of the original, so unless you can lift the 172 pound monster, it might not be the best investment. It is quite easy to make a similar dumbbell, however.
The dumbbell in the picture was made with a PVC handle. It has an outer diameter of 2 3/8 inches, almost exactly the same as the original. It is currently loaded to a weight of approximately 135 pounds. I won't explain how to make the handle. For a detailed explanation consult how to make thick handle bars.
One of the keys to making the simulation as realistic as possible, is to use a fairly wide handle. The handle in the picture is eight inches wide. It is important to grab the bar in the very center and not allow the plates to touch your forearm. Allowing the plates to touch your forearm makes the lift easier. It gives you an additional point of stabilization, and most importantly your forearm helps resist the rolling of the dumbbell. Rolling of the dumbbell is the main reason the lift is difficult.