Camden Bowen’s lost PLA casting engine project began as a reaction to waste: after machining internal combustion engine components from billet aluminium stock, he decided the sheer volume of material being discarded was simply too much to stomach, and set about learning to cast metal parts instead.
Casting is, in many respects, the more elegant path. Rather than cutting away everything that isn’t the final part, you pour metal into a mold shaped exactly like what you want. The challenge, of course, is making the mold in the first place, and that is where the real ingenuity of Bowen’s approach comes through.
Building the Kiln and Sourcing the Aluminium
True to his DIY instincts, Bowen did not simply order equipment off a shelf. He built his own kiln from cement and perlite, fitted with a propane burner, giving him the heat needed to process both the molds and the metal itself. For the aluminium, he sourced a stack of alloy wheels, specifically because the alloy used in their manufacture is well suited to casting. Those wheels were first melted down into ingots, a step that does more than just produce a convenient feedstock: it also helps to purify the metal before it goes anywhere near a mold.
It is worth appreciating the resourcefulness here. Alloy wheels are widely available as scrap, they are cast components themselves, and remelting them closes a satisfying loop. The ingot stage strips out contaminants and gives you a cleaner, more predictable pour when the time comes.
The Lost PLA Casting Engine Mold Process
For the casting method itself, Bowen chose lost PLA, a process that takes its name from the fact that the pattern is destroyed during mold-making. The intended shape is printed in PLA on a 3D printer, then surrounded by a mold material before the plastic is melted and burned away, leaving a cavity ready to receive molten metal. According to Hackaday, in comparable lost PLA projects the PLA forms are repeatedly coated in layers of ceramic slurry and silica sand over a week, building up a thick shell around each printed piece before any heat is applied.
Bowen’s own approach used Plaster of Paris mixed with sand to give the mold material the heat resistance it needed. The sand addition is not decorative: straight Plaster of Paris would crack badly under the thermal shock of molten aluminium, so the aggregate helps hold everything together. Getting the plaster mixture right took trial and error, and burning out all the PLA proved particularly troublesome.
The firing stage is critical. Ceramic forms used in lost PLA casting are heated to 870°C (1,600°F) to achieve full hardness and drive off every trace of the plastic pattern, as documented by Hackaday. Any residual PLA left inside the mold would vapourise explosively on contact with molten metal, so a thorough burnout is not optional.
After working through those difficulties, Bowen produced a usable mold and cast an engine cylinder with only a few imperfections. For a first serious attempt at lost PLA casting, landing a recognisable, functional engine component is a genuine result.
Why Casting Makes Sense for Engine Components
The comparison with subtractive machining is instructive. Milling a cylinder from billet means starting with a block of material, cutting away the vast majority of it, and ending up with a pile of swarf and a single part. Casting, by contrast, uses roughly as much metal as the finished part requires. Commercial engine manufacturers have understood this for generations, which is precisely why cast components dominate production engines rather than billet-machined ones.
Bowen’s project, drawing on a homemade kiln, recycled alloy wheels, a desktop 3D printer, and RepRap-lineage FDM technology, demonstrates that the fundamentals of foundry work are accessible to a determined home machinist. The Hackaday.io maker community has long championed exactly this kind of process transplant, and a cast engine cylinder sitting on a workbench at home is as good an argument as any for the approach.
The full build details, including the kiln construction and ingot preparation stages, are documented for anyone looking to follow the same path from 3D print to poured metal.
