Last year Wal-Mart carried a pumpkin foam project that had sticky eyes, nose, and mouths. Instead of using the foam pumpkins we put the sticky face parts on small pumpkins. It was really cute. I have not looked for this set this year but I bet you could find something similiar either at Wal-Mart or local craft store.
I have also seen rolling pumpkins in glitter and they look really good. This may be a little messy but the end result is something to talk about:)
It sounds like so much fun.....enjoy!