The one in the photo is made of rough-cut FSC-certified redwood, but they’re also great with recycled wood. The ones I personally use are cobbled together from odds and ends. Plywood makes for a smooth top without seams. The casters are 2-inch hard rubber.
I like attaching tin cans, power strips, and various containers.
Please specify whatever size you like. Trial & error favors these dimensions:
Height: 30 inches
Width: 20.5 inches
Depth: 19 inches