Hi! Still thinking about a small footprint Z axis mechanism for my self built CoreXY printer. I had the idea of using a kind of scissor mechanics underneath the print bed, but I think that will give a nonlinear Z movement, so I am wondering if Marlin (or any other firmware for Arduino+RAMPS) supports non linear Z axis movement?
Good point. So I’ll modify some parts to have more room on the back ti implement a more classic Z Axis 
The best one that i have seen is wire driven with the motor under the platform.