I think this is just beautiful! A simple tower made of three different pumpkins.
There are so many beautiful squash and pumpkin varieties available - check out this link to see my favorite photo guide of them on the web.
Do you know the phrase "Gilding the Lily?" It refers to when unnecessary adornment is added to something that is naturally beautiful.
I have seen some "paint, carve and glue" tips swirling around and I would like to suggest that you keep it simple.
Just gather a few beautiful shades together and let them speak for themselves. Mother Nature will spark far more comments than anything you can do with a glue gun.