Turning 3D Prints Into Metal Using Lost PLA Casting in a Backyard Foundry

I've been using the lost PLA casting method to turn my 3D-printed designs into solid metal castings from the comfort of my own backyard DIY foundry, combining modern technology with an old technique. Using a standard 3D printer and PLA filament, the first step is to design and print detailed models. Each piece is coated in a ceramic slurry after it has been printed, forming a shell around the plastic model. The piece is fired in a kiln following multiple dips and drying phases to construct a thick, long-lasting shell. This stage not only hardens the ceramic mold but also burns out the PLA inside, leaving a hollow cavity in the shape of the original print.

 Once the mold is prepared, molten metal is poured into the cavity to fill in the plastic that has evaporated. Once the metal cools and the ceramic shell is broken away, the result is a precise metal replica of the original 3D-printed model.  This technique is closely related to the traditional lost wax casting process but uses modern PLA filament instead of wax.

 A one-of-a-kind 40 mm-pitch M42 bolt was one of my standout creations. Unlike a typical bolt with a continuous helical thread, this design features ten individual grooves cut in each direction to accommodate both left-handed and right-handed nuts.  The modeling and casting of this unusual thread profile required extra care, but the end result is a striking mechanical part with form and function.

Check out Robinson Foundry's excellent video on the lost PLA process for a deeper understanding of this project's inspiration. This video is a great resource for both novice and experienced makers. This combination of digital design, ceramic shell casting, and molten metal opens up a world of possibilities for doing your own metalworking, whether you want to make art, make replicas of machine parts, or just enjoy the satisfying process of turning plastic into polished metal.