I have fantasized about, but never built nor even properly designed, a lift which would use an optical sensor to trigger a (hydraulic? magnetic?) lift arm - see the drawing, which shows a plan view. Ideally, I suppose, a second optical sensor mounted towards the outside would reset the lift to its lowest point when you moved the arm back out.
seems if some use magnets as a means for anti-skating, couldn't one use magnets for a lift?
obviously I was thinking about having the ability to adjust the distance between the magnets (and also trying varying strengths of them).