These turned out remarkably nice for such a cheap and simple activity.
The only necessary purchases are pastel colored spray paint, some water collecting trays to place under the can, and decorative stuff. We already had foam letters for writing names and phrases and foam designs. You can also buy fake flowers. They seem expensive, but other things can be used and they go a long way if you cut up the flower. Glitter glue also looked nice on the finished pots. Hot glue worked best for attaching items to the can.
One year, I saved cans when I dropped stuff off at the local recycle center and I collected them from a local restaurant another year.