Tie a pen to the end of a thread wound clockwise around a spool. Pull the thread taut and move the pen counterclockwise to unwind the thread. The pen traces a curve approximated by an Archimedean spiral: The distance from the pen to the center of the spool is nearly proportional to the change in angle made by the thread relative to horizontal.
Made in the UK from recycled plastic bottles, stretched over a lightweight recycled frame. Packaging is also made from 100% recycled content.
