I have found that the best way to encourage my children's creativity is to have the supplies on hand but no hard and fast rules about what they should be doing with said supplies. My son attended a Harry Potter camp this week and came home on Monday with great excitement: "Mom, I have to have a broom for Quidditch." I remember the scene from one of the first movies where Harry gets knocked off his broom in a storm and I feel grateful that the camp version will probably be played on the ground. Field trip to Target to pick up the appropriate broom as the one we own is, apparently, much too modern.
My son looks at the broom discerningly and states: "Quidditch brooms are not yellow. I need to paint this." Now, when I impose an art project on him, he finishes it in 3 minutes and has no connection to finished product. This time, it really looked like he was performing an operation of some sort. After the second coat, he asked me to paint "Nimbus 2001" in yellow and he pronounced it workable for the upcoming tournament.
Every evening he worked on some project for camp because his house was assigned points for each homemade item team members made. He made a hat, a wand, a crest, and a beautiful sign out of an old ski box. The amazing part of this story was that he found all the supplies and asked for no help. I was a bit stunned to not be consulted as the resident artist.
So the finished projects, although a bit rough, were all him. His pride of ownership was evident and his house won the Cup. I take my wizard hat off to his teachers who set up such a beautiful arena for those campers to shine...all on their own!