Method and apparatus for extending and retracting the writing element of a self-retaining writing instrument

A method for extending a writing element of a writing instrument, comprising:

• applying a stress to a bistable spring of the writing instrument, the stress being sufficient to transform the bistable spring from a configuration in which the writing instrument is coiled to a configuration in which the writing instrument is straightened,
• wherein the bistable spring has a first surface and an opposed second surface,
• wherein the transformation of the writing instrument from the coiled configuration to the straightened configuration automatically causes a flexible tube or material disposed in a longitudinal channel defined by a spring cover comprising a flexible material disposed on the first and second surfaces of the bistable spring to extend from an end of the bistable spring, the flexible tube or material comprising a writing element, and
• wherein an end of the flexible tube or material distal the writing element is anchored to the bistable spring or to the spring cover, such that the flexible tube or material is freely slidable at an end containing the writing element.