Water wall Love this. Also like the idea of something that is changeable.more flexible. But using wood is appealing and the water stays against the "wall" so it has the thrill of movement w/o getting children very wet. That's appealing.
This is great for mark making and lovely outdoor play on a hot day! So simple, no clean up! Fill up a trug with water, add mops, brushes, brooms, sponges, spray bottles. Sit back while your children play. Dipping their tools in and making marks all over the garden/pavement/shed. :)