Elf house on a tree! That would be cute in the garden, especially in the tree over grown with ivy. How about some battery tea lights in the windows during outdoor parties. I hear the fairies/elves whispering "home school project" in my ear.
Make cement cloth planters. Approximately a water/cement ratio. Add drainage holes in the planter before it completely hardens to prevent cracking. You may also want to apply a couple coats of cement sealer after the planter is dry.