SUPER COOL IDEA!!!! I love this, and anyone can do it... you don't have to paint the rocks the way it's shown...
As a matter of fact, when it get's warmer, we're going to do this ourselves... and I'm going to have my son use his regular paints to paint them. Then I'll use polyurethane and go over the entire rock. This will seal in his paints, while keeping them waterproof. Another variation, would be coloring one 'set' one color (to be the 'x') and the other half another color, to be the 'o').
Either way, this is a great garden showpiece, it's functional, and fun for the whole family!
Without further ado, here's a great garden tic tac toe!
a can of dark spray paint
white acrylic paint and a small paintbrush
10 or 12 smooth, flat stones
9 square tiles (mine were 6″ x 6″ slate tiles left over from our kitchen backsplash) or thin stone pavers.
The full tutorial is available at Northwest Edible Life blog!