I think the bases are PVC, I have made some stuff with PVC for the gliders but not a wheel base. I would think as long as you don't mess up the bearings (they seem high quality given how quite they operate.) you could make it yourself, the local hardware store here has tons of PVC pipes and parts and sizes. It would also probably cost less then $10.
I would suggest going BIGGER so it is stable and has NO chance to fall over and hurt a glider, I tie wrap mine to cage just to be sure the wheel can't fall.