Lady Bird & Bumble Bee Tic-Tac-Toe game - hand paint rocks and a tree stump for a home made outdoor game. Durable, low cost, fun + garden art! More creative ideas @ http://themicrogardener.com/gardens-for-kids/ | The Micro Gardener
Maybe mix gravel with colored rocks to add interest? Need to talk to someone about if I need to do anything to make it more durable. Like a glaze to keep the gravel together? Something laid below the cinder blocks to keep gravel and rocks in place??