As in elevators, that when taken down will close set of doors above you, that will block drop down movement. Also might have to change that elevator platforms cannot be dropped down from. Also if possible, make the elevator "base" which attaches to the background blocks as thin as possible, as to allow us to place wires for "detect if there's something on the elevator when it moves", and allow construction of a form of automatic elevators. Well, except for the wooden ones...
