Helices　are　ubiquitous　building　blocks　in　natural　systems,　and　have　since　become　major　sources　of　inspiration　for　engineering　design　of　helical　devices　with　a　range　of　applications　in　sensors,　transducers,　transistors　and　micro-robotics　devices.　In　this　work,　we　illustrate　the　mechanical　self-assembly　principle　in　spontaneous　helical　structures,　and　perform　finite　element　simulations　to　model　such　large　deformation　of　thin　structures　in　three　dimensions.　Our　work　can　facilitate　designs　of　tunable　helical　structures　at　both　macroscopic　and　microscopic　scales　with　desirable　geometric　parameters　for　engineering　applications　such　as　in　nanoelectromechanical　systems　(NEMS),　drug　delivery,　sensors,　acturators,　optoelectronics　and　microbotics.