I have been perusing the RS catalog and saw they sell a light duty linear guide that uses a bushing. That got me to thinking. What if I machined a polyethylene bushing for the profile aluminum? I ran a circular hole in some 12mm polyethylene and the aluminum profile rode on the corners only. It was really slippery. I am working on another design that has a little more mating surface to the profile to try that tomorrow. Seems like a interesting possibility.