Paint craft pumpkin with green paint. Add a second coat if needed and let dry completely.
Use a black marker to draw an outline of the eyes, then add the nose.
Fill in the eyes with yellow paint.
Use the black marker to add eyelashes and eyebrows.
Once the yellow paint has dried completely, add details to the eyes. The Grinch's eyes have kind of a thick black horseshoe shape in the middle.
Use the marker to give your Grinch a wide, mischievous smile. It should extend to just under the ends of both eyes.
Take your Santa hat and fold the white trim so that only half of it is visible. Secure it in place with hot glue.
Stuff the hat with craft stuffing, cotton, paper or even plastic grocery bags (you can use whatever you have handy). Use hot glue to attach the Santa hat to your pumpkin. Finally, fold the hat over slightly and hold in place with a drop or two of hot glue. Let the glue set and now your pumpkin is ready for Halloween fun!