For the 2026 London Design Festival, three Taiwanese designers turned the city's discarded bubble tea leaves and used coffee grounds into large-scale 3D printed furniture and lighting, according to a report from designboom. The project, called "After the Last Sip," ran September 12-18, 2026, and treated everyday café waste not as a filler to be hidden inside a finished product, but as the visible, defining material of the work itself.
The team behind the project — Chao-Chun Kung, Ching-Yu Lin and Chen-Yang Chang, with spatial curation by Chih-Han Liu — sourced their raw material the way a local roaster might source beans: by going shop to shop. They gathered used tea leaves from London's bubble tea vendors and spent grounds from neighborhood coffee shops, according to designboom's coverage. Both waste streams are produced constantly and in volume in a city with London's café density, and both are ordinarily thrown out rather than put to any further use.
Rather than composting the residues, the designers dried and ground them into a fine particulate, then compounded that particulate with PLA to create a printable composite. It's a process that will sound familiar to anyone who has worked with coffee-infused or wood-fiber filaments — organic waste ground fine enough to blend into a thermoplastic matrix — but "After the Last Sip" pushes the idea past desktop filament spools and into architectural-scale robotic fabrication, per VoxelMatters' report on the exhibition.
Testing the Material Before Trusting It
Before any large piece went to print, the team ran a structured material-testing phase on the tea-and-coffee-PLA blend. According to designboom, the designers evaluated how three variables — particle size of the ground residue, the composition (the ratio of organic material to PLA), and the blending method — affected four outcomes: color, surface texture, translucency, and structural behavior under print conditions.
That's a familiar checklist to anyone who has formulated a composite filament, but it matters more than usual here because the finished objects are meant to be judged by eye as well as by function. A furniture piece or light fixture made from a biocomposite lives or dies on whether it looks intentional rather than experimental, and translucency and color shift are exactly the properties that swing between "warm, organic surface" and "muddy, inconsistent print" depending on how much tea or coffee fiber is loaded into the matrix and how coarsely it was ground. Structural behavior — how the loaded material handles the shear and layer-adhesion demands of large-format printing — is the harder engineering constraint underneath the aesthetic one, and it's the variable that ultimately gates how large and how load-bearing a piece can be.
From Parametric Models to Robotic Arms
With a validated material recipe in hand, the designers moved to production using parametric design methods paired with large-scale robotic 3D printing, carried out at Fab.Pub, a digital fabrication space in East London, according to both designboom and VoxelMatters. Parametric modeling — defining a form through adjustable rules and constraints rather than fixed geometry — is a natural fit for a project exploring a variable, waste-derived material, since the print parameters and the material properties can be tuned against each other rather than treating the composite as a drop-in replacement for standard PLA.
Robotic arm printing, as opposed to a conventional gantry-style FDM printer, is what makes the furniture and lighting scale possible in the first place. Robotic systems aren't boxed in by a fixed build volume in the way desktop and even large-format cartesian printers are, and they can lay material along non-planar, sculptural toolpaths that would be awkward or impossible on a standard three-axis machine. For a project built around organic, irregular forms, that flexibility in toolpathing is as important as the material science.
The resulting body of work includes named individual pieces — CHA (茶), Iced Tea, Undetermined Shore, Nexus Bloom, and Unfolding Bloom — spanning furniture, lighting, and standalone sculptural objects, according to designboom's exhibition coverage.
Crucially, the designers made a deliberate aesthetic choice to leave the fabrication process visible. Printed layer lines and the particulate texture of the ground tea and coffee residue remain on the surface of the finished pieces rather than being sanded, coated, or otherwise finished away. That's a departure from most commercial 3D printed furniture, which tends to treat visible layer lines as a defect to be minimized. Here, the layers and the particle texture are the point — visual evidence that a chair or lamp was built, additively, out of a city's leftover drink waste.
What It Means for Makers
"After the Last Sip" is a useful data point for anyone experimenting with organic-waste-loaded filaments at desktop scale. The particle-size, composition and blending-method testing regimen the team ran — checking color, texture, translucency, and structural behavior against those three variables — is essentially the same methodology hobbyists use when dialing in a home-ground coffee-PLA or wood-PLA blend, just applied with more rigor and at architectural stakes. It's a reminder that loaded biocomposites aren't a single material with fixed properties; they're a design space, and the print quality you get depends heavily on how finely you grind your waste stream and how much of it you load in.
The project is also a signal about where large-format and robotic printing are heading in design practice: toward materials sourced hyperlocally — literally from the cafés down the street — rather than shipped in as commodity pellets or filament spools. For makers without access to a robotic arm, the more immediately actionable takeaway is the surface-finish philosophy: rather than fighting visible layer lines and particulate inclusions in a recycled or bio-loaded print, "After the Last Sip" makes the case for embracing them as the material's own signature, not a flaw to be printed around.
