In this activity, the idea of negative shapes is introduced using three different geometric shapes (sphere, cube and ovoid) along with cups to hold them each and a handy little storage/carrying tray.  Each of the three shapes measures 4.5 cm (about 1.75") in diameter, and are made of solid hardwood with a natural finish.  The tray measures 25 cm x 20 cm (about 10" x 8") and has loop handles.