Scissor Lifter?

[Nemo]

Two more things that make scissor lifts hard:

1) One or both of the bottom sections has to slide across the bottom surface as it extends upward. Getting that to work smoothly with low friction and without wobbling around is tricky.

2) Powering a scissor lift without hydraulics is hard if you're lifting a decent amount of weight. When it's fully retracted, you have to supply a lot of force to get it started, because the initial angle is unfavorable. Certainly it can be done with motors, but I think it's a lot trickier than powering an elevator or an arm.