The smaller the washer, the lower will be the friction. The following sizes are supplied in 4" lengths:
White, .012" ID, .032" OD
Red, .015" ID, .033" OD
Blue, .022" ID, .042" OD One length of each is supplied in a package
An easy way to make washers is to hold an electric drill in a vise. Push a piece of straight music wire, smaller than the tubing ID, into a short piece of tubing and clamp it in the drill chuck. Turn on the drill and slice off washers with a razor blade. They will be captured on the wire and will have parallel faces. Washers can range from .010" to .040" thick without affecting model weight significantly.
Teflon has its lowest coefficient of friction when heavily loaded. Friction torque is proportional to washer diameter. Therefore, the lowest torque is reached with very small diameter washers. This tubing accomplishes that goal.