Pop the popcorn and remove any unpopped kernels.
Place the popcorn in a large bowl and set it aside.
In a large pan, add the butter and melt over medium-low heat.
Add in the marshmallows and continue to cook stirring constantly. The mixture will burn quickly if not.
Remove from heat when the marshmallows are melted. Add in the food coloring and vanilla and mix well.
Pour this over the popcorn. Gently mix until the marshmallow mixture coats all the popcorn.
Form the popcorn balls, squeezing tightly to hold their shape.
While the balls are still hot, press the sprinkles and candy eyes all over each ball. If you are using candy corn or other candy, press them into the balls as well.
You may need to press the balls together again as they start to cool.
When they have cooled all the way you can package them. Wrap individually or store in an airtight container.