So, I can see that this won't make it into the game, since it'd be incredibly hard to program, but I'd love to see a mechanic where you have, say, a spring attached to 1 face of a block, and if you rotate it, the spring would have to extend and coil around the block to stay attached, something reminiscent of a winch, but instead of having it as a block, having it as a mechanic of rope/spring/chains. 

I was really hoping this was in the game already when I was attempting to create a catapult with a more varied (coilage, torque?) than the current spring settings.