I just completed my first moxon vise after a few projects that were designated as "practice" for hand cut dovetails. My bench is rather tall to begin with but I really wanted to be able to get ends of wide boards/panels up and into a vise. The finished height is 3-1/2" and the width between screws is 24-1/2".
The threaded ends of the dumbell handles were 4" long, so even with a movable jaw that is 2" thick, I still have 2-1/4" of opening.
I removed one of the stop flanges from each handle and used the other inside the rear lamination. The fixed jaw is made of three pieces of pine at 3-1/2" (call them A) and two pieces that are 1-1/2" (Call them B) . Two pieces of A are glued together and the next day two pieces of B are added. There are dadoes cut into B where the 1" Acme thread passes through. The last piece of A is drilled out for the barbell shaft (1") and the flange is countersunk 1-3/8" diameter about 3/8" deep into it so the last "layer" can match up easily with the 3-1/2" height.
The star knobs are easy and quick to spin on the Acme threaded rods. I lined the outer (movable jaw) with leather and I spent a total of $17 for the dumbells and two 1" washers for the front knobs. I had the leather, pine and the "mahogany" material on hand.