I just finished my rolling base a couple weeks back… I designed it over a year ago… I am pretty slow. 
I have almost the entire thing modeled in Fusion down to the washer on top of the hockey puck. I was going to cut a custom one so I could cover more of the top of the puck… but ended up just using one off the shelf. I did the modeling as an exercise to learn assemblies and joints for a future project. I did a short video on the leveling casters. I am planning on posting the components on Fireshare. I just wanted to make sure everything worked before I did. Here are a couple of pics.
I plan to take some more pics once I get the table back together.
Components List:
(4) Base plate
(4) 3-1/4” L3x3x3/16 angle
(4)Caster mount plate
(8)Gusset plates
(4) 9” 3/4” T rod
(12) 3/4” hex nut
(4) 1/4 spring pins
(4) hockey pucks
(4) 3/4 flat washer
(4) 1/4x1-1/4 fender washer
(4) 1/4-20 x1/2” cap head screws
Frame Tubing… I used 14ga 3x2 and 2x2 tube because I have a bunch of rejected remnant from a local treadmill manufacturer… use whatever. If you want any dxfs of the cnc cut components, you are welcome to them.