The reinforced door is suspended from a heavy duty track. At the moment, the door slides smoothly with the assistance of a weight on the end of a Dyneema cord running through a pulley, but it’s not automatic.

I could motorise it, but that could quickly lead to crushing results. A chain-driven mechanism powered by a worm-drive motor would be practically impossible to move, negating the need for a lock, but it could also trap someone inside or squish them. To avoid this, I could power the door open but allow it to close using only a counterweight.

Work in progress. Next I need to figure out a locking mechanism.