This is a replica of the piston in Minecraft, there is a small crank on the side of it which you can turn and then it will extend, it goes about half way out. This particular version was actually designed with silver in mind as the printing material, but would work with any material that has a min wall thickness of 0.6mm or less. Assembly required and its a very simple assembly. glue might be needed to close it up.
NOTE: this model has not been printed yet, it is not guaranteed to work, but Im quite sure it will :)