Spirograph, a plastic toy used to draw curves(hypotrochoids). Picture taken from a specimen produced and sold in the USSR (ОСТ 6-19-417-80 and 14МО.390.319, article НК-9) and kept in author's private collection.
<a href="//commons.wikimedia.org/wiki/User:Alexei_Kouprianov" title="User:Alexei Kouprianov">Alexei Kouprianov</a>
CC BY 2.5
<span class="int-own-work" lang="en">Own work</span>