Prison Cube

This is my design for a large "prison cube" to trap a player within a 2 block zone at the center of a self-repairing 12x12x12 cube.

A video of the device in action can be found at: youtu.be/ZIwwoAu9vMk

Here is a video of the cube being generated: youtu.be/CeA1derrbMc

For a more detailed look at the design, check out the screenshots at: imgur.com/a/pE2oq

The design could be compacted quite a bit and still be as effective. I believe that anything larger than a 5x5 cube would be sufficient so long as the player did not have a high efficiency pickaxe.