The children in art class experience what it's like to draw with their feet and mouths (and elbows! This is not only a fun, action art experience, but it gives them a new appreciation and gratefulness for their hands.
Saw these style boards on Oriental Trading for use as geometry boards. Wondered a diy hack. Use glue on bottom circle of thumbtack to secure it from being plucked out by little fingers. Sowdering About in Seattle: Toddler Busy Boxes