Last time we checked in with YouTube’s King of Random (AKA Grant Thompson), he was teaching his 3-million YouTube subscribers how to create a backyard foundry for melting down recycled aluminum cans for use in other projects.

Well, the self-described “Mad Scientist” is at it again and this time, he’s teaching those who have followed along with his previous projects how to use the backyard foundry and aluminum ‘biscuits’ for casting prototypes using rough styrofoam prototypes. In this case, he turns “Styrofoam Into Solid Aluminum” using a “lost foam casting” technique – a similar (albeit more dangerous) technique to lost wax casting.

“I spent over 100 hours of time, and 7 styrofoam prototypes to make this video. About a third of the time was spent filing and sanding the gun. Each time I poured a casting for the gun, the trigger guard wouldn’t complete all the way through, so I kept making new styrofoam guns, modifying the designs slightly until it worked,” said Thompson.

“Once I got a fairly clean casting, I put 2 days into filing down rough points, and sanding them smooth.”

To create the final product, Thompson starts with a foamcore model that he’s divided into layered cross-sections that he attaches to create a thicker, three-dimensional form. Of course, if you have access to a CNC or prefer to use traditional shop tools, you could do something similar with any number of other foam materials that are traditionally used in the prototyping process.

Once the final form was achieved, a riser/spout is attached to a strategic pouring location before being placed into a bucket of sand. Once the aluminum cans have been melted (and you are presumably keeping anybody under the age of 11 at least 20 feet away), the molten metal can be poured directly on top of the riser/spout where it immediately vaporizes the foam and fills the form with liquid aluminum. After approximately ten minutes, the final metal form can be taken out of the sand using a pair of pliers before being finished with any number of metal polishing techniques.

In the case that sand casting a larger object is desired, you could always take a lesson out of designer Max Lamb’s playbook and head to your local beach:

Remember kids, safety first!