Hi mimi :D
Withies would be ideal to make a topiary structure. You can buy them from craft shops in a bunch. (They aren't expensive.) Soak them in the bath for a couple of hours and they are fab for allsorts of shapes etc... Just use garden twine, clear sticky tape or masking tape to join together. You can even make garden lanterns etc with them and they blend in ever so well as they are natural. They last for ages too!
As well as topiary you can make any type of structure/ design and put it in the garden, looks really cool 8)
Regards - CF