 In the last years of his life, Zuse conceptualized and created a purely mechanical, extensible, modular tower automaton he named "helix tower" (""Helixturm"").The structure is based on a gear drive that employs rotary motion (e.g.provided by a crank) to assemble modular components from a storage space, elevating a tube-shaped tower; the process is reversible, and inverting the input direction will deconstruct the tower and store the components.