Depends on what you want it to look like. You could get some scrap vinyl flooring and cut it to shape. That way you get to pick any of the gazillons or color and patterns available. Or you could assemble a really snazzy one of of a few sticks of laminate flooring and some matching quarter-round molding (they make molding that snaps into the grooves on the underside of the laminate). Spray-glue a sheet of foam or felt on the underside to keep it from sliding around and help to hold it together, and you're good to go. If what you want is one of the common, semi-flexible clear plastic ones with the carpet spikes underneath, you're better off just buying one.