Ace hardware has 70mm furniture slide disks for about 7 dollars for 4. I used a 5/16" stainless bolt for an axle.

I removed the white self-sticking layer and sandwiched two of them together back to back to make a durable, light weight skeg wheel for occasional use on my small dinghy.

Don't try to drill out the metal washer (it will spin and melt the plastic). Cut the black rubber on the back and remove the fender washers.