I have been admiring living willow structures for a while now. Common willow objects include tunnels, figures, furniture, and shade structures. These are much more common in the UK than they are here in the States. Almost any idea that you can hatch for some sort of cool, 3D shape is possible to create. After the planning is done on paper, you need a source of willow branches (called rods) that are straight and pretty long.
Willow branches (if not allowed to dry out after being cut) stuck into the ground will often root and grow (trying to turn into willow trees!). Willow branches have amazing rooting powers (you can soak them in water for 24 hours, and then use the liquid as a rooting compound for other types of plants). Juvenile willow plants are very flexible and are shaped rather easily. Branches can be tied to one another or a support structure with simple twine. Over time, branches may fuse and grow together.
Our willow dome is approximately 12 feet in diameter, and 6 feet tall. It has two doors and a window. It took about 80 9′ willow rods to construct. It will take a year for the structure to root and begin to establish itself. During this time, the dome will be roped of so that it may stay healthy and grow strong. Next year the dome should be ready to play in!