[Al Skierkiewicz]

Small Parts sells aluminum tubing in graduated sizes that are intended to fit inside one another. You will still have the problem of how to get a lift to work with the small tolerance between sizes.
Be careful when purchasing off the shelf aluminum tubing, it may not be extruded. This tubing although theoretically able to nest inside each other, has some added material on the inside that prevents the tubing from sliding inside a larger piece. (This experience comes from trying to build vertical antennas out of tubes that start at max diamter of 1-1/2"' and go down from there.)