Based off Inspyre 3D's Jack Skeleton pumpkin ( https://www.myminifactory.com/object/3d-print-jack-skellington-pumpkin-75734) from the October Alien3D UFO box, I used the harry potter themed stencils and created a reverse image in tinkercad. I then used the pumpkin model to create a curved surface on the stencil and used what was left to create a carved in look without going all the way through. The model is about 171% of Inspyre 3D's original pumpkin size and still looks super good with a simple tea light inside the pumpkin.
I printed mine without supports, you can see there were some minor issues but you cant even see them from a short distance away.
Update: Just added a remix of cerberus333's Sorting hat, slightly modified to include the insert from the pumpkin top so that it fits on top of the pumpkin. You will need supports for the hat.
Also small post processing, you might need to sand down/trim the inside of the pumpkin to get the tops to fit perfectly. I just took a deburring tool to mine and it was perfect.
3D Solutech PLA