A Fully 3D-Printable Thermoacoustic Engine Now Runs on Biogas

A French engineer known as [my engines] has pushed his open-source thermoacoustic Stirling engine to a new milestone: the hot end and burner are now fully 3D printable in metal, and the entire design runs on homemade biogas. The project shows how additive manufacturing can turn a precision energy system into a DIY build.

How It Works

Traditional Stirling engines use pistons, crankshafts, and seals to convert heat into motion. A thermoacoustic engine does away with most of that. Instead, it turns heat into high-amplitude sound waves, then harvests those pressure waves to generate power. The result is an engine with almost no moving parts in the hot section, which means less friction, less wear, and a simpler maintenance cycle.

The latest version integrates a biogas or methane burner directly inside the 3D-printable hotend. That is a meaningful design change. Earlier prototypes used externally mounted burners, which made the assembly bulkier and less efficient. By printing the burner geometry into the hot end, the designer created heat-exchange channels that would be almost impossible to machine by hand. The 3D-printed structure also lets the team tune the internal passages for better thermal transfer.

Why SLA Metal Printing Matters Here

The hot end operates at temperatures that would deform standard thermoplastics. The solution is SLA metal printing: a vat photopolymerization process that uses a resin loaded with metal particles, followed by sintering to produce a solid metal part. The process can produce the fine internal channels and thin walls the engine needs without the tooling costs of conventional CNC machining.

For makers, this is the practical breakthrough. The rest of the engine—the compliance sphere, the feedback loop, the coolers—can be printed on standard desktop FDM machines using high-temperature filaments. Only the hot section needs metal SLA, and service bureaus now offer metal sintering at prices small projects can justify.

From Waste to Watts

The engine is designed to run on biogas generated from organic waste. [my engines] operates a homescale biogas plant that feeds methane into the burner, supplementing a solar installation at night or on cloudy days. The combination gives him a continuous, net-zero energy source that does not depend on the grid.

The power output is modest, but the real value is in the platform. The design is open source, with 3D models, drawings, and build instructions published at OwnEnergy.org. There is also a Discord server and a forum for collaboration. The project explicitly invites engineers, students, and energy enthusiasts to iterate on the design, test alternative working gases, and improve the heat exchangers.

The Bigger Picture

Thermoacoustic engines are not new, but they have spent decades in labs rather than garages. What changes now is the price of entry. Metal 3D printing has fallen enough that a single hot-end prototype does not require an in-house machine shop. Open-source licensing means the design can spread without patent barriers. And biogas infrastructure is becoming common enough at the household level that a maker in a rural area could realistically build both the digester and the engine.

The project still has technical hurdles. The thermoacoustic cycle needs optimization, and the team is evaluating linear generators and rotary turbines to convert the acoustic power into electricity. They are also testing helium as a working gas to boost efficiency. But the fact that the hardest part—the metal hot end with an integrated burner—is now a printable file changes the timeline for anyone who wants to build one.

For the 3D printing community, the story is a reminder that the technology's most interesting applications are not always consumer gadgets. They are sometimes precision mechanical systems that used to require a factory, now reduced to a model file, a spool of filament, and a sintering service.