Milk style jug (no matter the size)
Orange Paint (preferably pumpkin orange)
Sharpie or gel pen
Wire or String
Step 1: Cleaning
Be sure to take the labels off.
Then set to dry.
Be sure to keep the cap, or else your Jack-o-lantern will not have a top.
Step 2: Trace and cut
Cut out your design with a hobby knife.
Don't worry about the big dip in the jug, continue cutting as if it is not there. When the product is done and glowing, you will not even notice it is there.
Keep in mind that this plastic is very soft, so it is easy to over cut. If this happens, you can mend the cut with some good ol' super glue.
Keep in mind that you may decide to not cut a design into the jug, and rather, paint a design onto the jug. This can allow for some very neat effects.
Be sure to keep your scraps! This is type #2 recyclable plastic and should be treated as such. (This means that you should go and recycle them)
Step 3: Painting
Then add about two coats of orange (preferably pumpkin orange).
Too many coats will leave you with a very dull glow, and too few coats will give you a very bright glow.
Set to dry.
In these picture and subsequent others, you will see that a black undercoat and give a very strange effect to your pumpkin.