Variable depth rolling pin - video

Variable depth rolling pin. By Morgan Hurst. 8:37 video:

https://www.youtube.com/watch?v=CklH-sq8peM

I made something similar for my girlfriend for pottery. The rolling pin was just a piece of pipe, but the table had a metal frame, and the whole table could be lowered below the perimeter frame. That way the rolling pin rolled on the frame to maintain an adjustable distance from the table surface. Pottery stuff. I don't really understand it.

I taught a ceramics class early in my career. We just used wood slats of various thickness to get slabs any thickness needed.

I do not see the variable depth of that rolling pin. Do you just use different size disks on the end?