Technology — 3D Stone Printing

Design

The digital solution behind hardware and material science

We control each aspect of the design-to-production journey.

From a sketch: Sketches and drawings are enough to start. We develop the 3D model with the designers.
The right material: Custom materials are possible. We optimize the mix to achieve the desired performance.
Digital twin: The process can be completely simulated to avoid failure, optimize production and reduce costs.
Ready to print: Slicing, G-code and print bed optimization are generated from the model, with no manual setup.

Print

Geopolymer binder jetting

The printhead jets a liquid activator into a powder bed made of recycled mineral aggregate, only where the part is.

Where the two meet, a geopolymer forms and binds the grains into stone. Layer by layer, the element grows inside the powder. Everything around it stays loose and goes back into the next print.

01
Spread
A thin layer of mineral powder is spread over the bed.
02
Jet
The printhead jets the activator only where the part is.
03
Bind
The geopolymer hardens at room temperature. No kiln, no autoclave, no cement.
04
Recover
The element is lifted out. Unbound powder goes back into the next print.

Proof

Tested over 9 years of research at ETH Zurich

37 MPa: Mean compressive strength, in independent accredited tests
No loss: of strength after freeze–thaw testing
Fire resistant: Non-combustible and insulating, with no resin and no cement

Compressive strength (MPa), in-house tests per machine generation. Dashed line: independent test by a UKAS-accredited laboratory, 2026.

Finish

Robotic polishing and milling

A robot arm finishes each element, following the same digital model it was printed from.

Surfaces are polished where the design asks for it, and the printed texture is kept where it doesn’t. Faces and joints are milled to tolerance, so elements fit together in assemblies.

As printed
The grain of the print, left as it is. Rough and matte, like split stone.
Sandblasted
Even and matte, the layers softened.
Milled
Flat faces and sharp edges, cut to tolerance.
Ground
Smooth to the touch, the grains cut open.
Polished
A deep shine that brings out the colour of each grain.

A robot arm standing on a pallet inside a shipping container — The finishing robot, installed in its container.

More about our hardware →

Alternatives

Why our process works

Traditional methods and more recent printing processes each offer only part of the solution.

Alternatives	Freedom		Precision		Performance				Economy
Alternatives	Material	Form	Accuracy	Finishing	Strength	Outdoors	Fire	Sustainability	Cost
3DSP	Yes: Real mineral stone, with the grain, weight and feel of natural stone.	Yes: Any shape: undercuts, cavities, lattices.	Yes: Printed to the dimensions of the 3D model, piece after piece.	Yes: Crisp edges and a stone surface, ready to use or to finish.	Yes: Strong enough to carry loads, like natural stone.	Yes: Made for outdoors: it takes rain, frost and sun.	Yes: Mineral through and through: it does not burn.	Yes: Made from quarry and demolition residue, cured at room temperature, no cement.	Yes: Low-cost residue as raw material and no moulds, so even one-off pieces are affordable.
CNC-milled stone	Partly: It is natural stone, cut from a block. Composite stones require the block to be formed first.	Partly: The tool only reaches what it can see: no undercuts or hollow forms.	Yes: Milling machines cut to tight tolerances.	Yes: Fine detail and polished surfaces are possible.	Yes: As strong as the stone it is cut from.	Yes: Natural stone lasts outdoors for centuries.	Yes: Stone does not burn.	Partly: Needs quarried blocks, and much of each block is cut away.	No: Quarried blocks and hours of machining make every piece expensive.
Quartz-resin engineered stone	Partly: Crushed quartz in resin: stone-like, but uniform.	No: Comes only as flat slabs.	Yes: Slabs are cut to precise sizes.	Partly: Polished flat faces; edges can be shaped, but no relief.	Yes: Hard and strong, as a slab.	No: The resin fades and yellows in sunlight.	No: The resin binder can burn.	Partly: Some recycled content, but it relies on resin.	Partly: Standard slabs are affordable; custom shapes are not.
Concrete printing	No: Just concrete paste, not stone.	Partly: Layers stacked on top of each other: limited overhangs or cavities.	Partly: Extruded layers hold dimensions to the centimetre, not the millimetre.	No: Limited. Usually, the layers stay visible on the surface.	Yes: Concrete carries loads well.	Yes: Made for outdoor building.	Yes: Concrete does not burn.	Partly: Can take some recycled aggregate, but relies on cement.	Partly: Fast printing, for large elements, but high cement content.
Resin-bound sand printing	No: Sand held together by resin: it looks and feels synthetic.	Yes: Prints any shape in a bed of sand.	Yes: Precise, as it is made for foundry moulds.	Partly: Sharp shapes, but a sandy surface that needs a coating.	Partly: Strong enough for moulds and indoor pieces, not for loads.	No: The resin ages in sun and weather.	No: The resin binder burns.	No: Uses new sand and a petroleum-based resin.	No: The resin and new sand make large parts expensive.
Selective Cement Activation (SCA)	Partly: Cement-looking elements, not the texture of stone.	Yes: Prints any shape, like other powder-bed printing.	Yes: Fine powder allows precise dimensions.	Partly: Fine powder gives a smooth surface and sharp detail.	Yes: Suited to carrying loads.	Yes: Like concrete, it can be used outdoors.	Yes: Mineral, so it does not burn.	No: Needs fine, processed powder, not raw residue, and uses cement.	Partly: Cheap sand and cement, but costly machines and long curing.

Printed with GeoBJT

All applications →

Three technologies at the core

Materials, hardware and software, all developed in-house. The materials set the recipe, the hardware shapes the stone, and the software controls every step.