The process of making the heat-formed milk jug skull is straightforward -- you'll be using a heat gun to melt the HDPE plastic until it starts to become transparent, then press it into the details of the reference skull using a damp sponge. The sponge molds the plastic into the shape of the underlying form and cools it once it's in place.
Below are some process photos to give you the gist of it, then we'll go into more detail!
If you plan to fit the original skull onto a stand, you may need to cut a hole in the base first.
The original prop skull may have a movable jaw -- you can use a bit of hot glue to keep it from moving.
If mounting the skull, place a bit of hot glue on the top of the stand and then fit the skull onto it.
Prep the Milk Jug
Mark a line around the neck and handle of the jug, then cut this part off with a hobby knife.
Then, to allow the jug to fit over the original skull, cut a slit from the base in the back up to the top of the skull. NOTE: the milk jug is now oriented upside down to match the shape of the skull.
Cut a few slits where the jug will fit under the jawline.
You can now fit the milk jug over the skull.
Heat and Press
Your now ready to heat the plastic and press it into the original skull like a mold or form. Use the heat gun on high heat setting, and move it around a small area, such as the forehead or eye socket until the plastic becomes clear.
Then, wet and ring out your sponge so it is damp but not dripping. Press the melted plastic into place.
You'll repeat this until you're finished! This timelapse will give you an idea of what the process looks like.
Remove Skull from Form
Use a hobby knife to slit the top of the skull toward the back and down.
Peel the new skull off of the form skull.
Next, we'll wire up the lights and sound!