Is there a way to have a mesh extrude or retract itself during an animation while rigging with bones? Basically, I've got this mechanical mesh I'm making where I need a lid to hinge down to cover the top of a cylinder-ish shape.





This hinge is rigged to the lid. It rotates from a 45 degree tilt to a 90 degree tilt as the lid closes from a 90 degree tilt to a 0 degree one. 



See? The bottom part of the hinge extends through the bottom of the mesh. Do you guys know a quick fix?



When I try to make this hinged lid shut, part of the hinge sticks out of the bottom of the mesh. What would you guys recommend I do? If I flat-out shorten the bottom of the hinge arm, then it won't connect correctly and would look like it's floating. If I keep it like it is, the hinge can be seen poking through the bottom. What should I do?
Add a stretch to constraint to the bone that deforms the connecting rod. In the constraint settings you will also want to set volume variation to 0.0 so that the connector doesn't shrink as it gets stretched.