One of our images used in Big Dreams Small Spaces BBC2 was this one of an old tin bath dressed with miniature pink waterlilies – Nymphaea Pygmaea Rubra that love the depth of this container at 12 inches deep. They are flowering really well in the sunshine.
Remember to add a submerged oxygenating plant too so that the water will stay clear and healthy. We had been using 10ml of the liquid concentrate Extract of barleystraw weekly too in this container so that green water algae was inhibited.
Just shows that any container that holds water can be used to create a container pond for the garden and add water to the smallest of garden spaces.