The treads were made from a sheet of 36" x 36" neoprene rubber 1/4" thick that I found on Ebay for about $20. I first cut it into two 18" x 36" pieces. I then cut one into 3/4" x 18" strips with a razor blade knife. I then began glueing them across the other 18" x 36" section with Plumbers Goop glue using a piece of 1/4" plywood to get the proper spacing. Once they were all in place I covered the whole thing with a sheet of plywood and stacked several cases of beer on top to make sure all the strips glued evenly. This is very important since these treads will be bent and you don't want any of the pads to peel off. I then, with a red pen, marked on the back of the finished sheet lines showing where to cut to produce the finished treads. Eight sections joined in twos to produce the four treads. Cutting through the now 1/2" thick rubber with a razor blade knife seemed like too much of a pain so I used a hacksaw. It was more like ripping than sawing. Reminded me of cleaning fish or cutting large slabs of meat. DO NOT attempt to cut the treads on a table saw. Oh I know it might be tempting, perfect cuts, quickly done. Trust me, the rubber grips the saw blade like a brake. Noise, smoke, bad smell, bucking rubber, bad scene. Done it - don't go there, trust me.
Here are the feet getting covered with styrene plastic. The plans called for .020 thickness, but Tap only had .040 thickness. That's still only 1/64th" thick. I thought this would be an improvement since it would double the strength of the toe area, which has no wood support behind it, and also would decrease the chance of the glue over softening or melting through the plastic. It also had a textured back that I thought would make the glue grip better and at about $25 for a 4' x 8' sheet not a bad buy. You can also see the casters mounted to the mounting plates, before installation, on the right side of the picture.