Nature lovers will enjoy this tic-tac-toe set. Gather a wood cross section, twigs, four tiny pebbles for the intersections, and eight rocks in two different colors. Clean the cross section with a damp rag. Use a pencil or piece of chalk to draw a grid onto the wood. Break twigs into 12 pieces to fit the grid. Glue the twigs and small pebbles along the grid on the cross section. Let the glue dry. If you like, spray the surface with clear gloss.