[Jared]

On the outside, we have 2" x 1" .125" wall rectangular aluminum tubing with some lightening pockets. The carriage has 8mm ID 22mm OD shielded bearings that roll on the 2" x 1". Our preliminary testing showed that delrin rollers didn't roll very nicely when loaded with 50 lbs cantilevered out a foot from the lift tower when the vertical distance between bearings was around 5", but ball bearings ran much more smoothly.