This structure serves as one of the rest facilities built for Expo 2025 in Osaka, Japan. As part of the project, 20 rest facilities—including toilets, rest areas, satellite studios, and pop-up stages—were each designed by a young Japanese architect selected nationwide.
We used a construction 3D printer from WASP capable of extruding earth to design a canyon-like architectural and landscape installation. The primary material was soil—a primitive and locally available substance. Though heavy, fragile, and far removed from modern industrial materials, soil has the advantage of being able to return to the ground. By using it as a new construction material, we aimed to propose a vision for future architecture and society—one where people build their own nests using soil from their local land.
The printed material was composed of soil, clay, hardening agents, straw, pigments, and seaweed glue—selected with inspiration from Japan’s traditional earthen wall construction methods. These components were chosen not only for their strength and printability, but also for being entirely locally sourced within Japan, and biodegradable after the expo concludes. The hardening agent, magnesium oxide, reacts with water and soil to set; once printed, the elements were cured in a humid environment for three days, then dried to achieve sufficient strength.
The printed forms are based on the organic curves found in nature. We 3D-scanned and sampled stone shapes collected from various regions across Japan and fused these into composite geometries. Additionally, through physical testing, we derived the structural logic necessary for soil to stand independently, and performed form optimization under the constraints of overhang tolerances to determine the final shape.

We 3D-printed the following four architectural components:
1. Exterior Panels
The building’s outer panels were fabricated at a factory in Toyama and transported to the site for assembly. A total of 56 panels were mass-produced, each measuring 930 mm in width, 300–400 mm in depth, and 1200 mm in height. After fully drying, the panels were transported by truck and lifted into place by crane to be attached to the timber-framed structure.
Each panel surface had a unique form; when placed side by side, they collectively created a texture reminiscent of a natural rock face. To avoid damaging the earthen material, wooden inserts were embedded during printing, into which screws were later driven to fix the panels to the frame. Since printing and transporting panels of this size had not been done before, we developed the entire process ourselves—from printing techniques and logistics to crane handling and installation.
2. Bench Planters
We brought the 3D printer onsite and fabricated planters that also function as benches and tables—for both people and plants. Using the printer’s full build volume (6.2 meters in diameter and 1.7 meters in height), we produced four sets of these installations at various locations within the site. The planters took diverse forms—such as C-shapes that surround visitors or multiple clustered “islands”—creating spaces for rest that encourage various modes of occupancy.
3. Earthen Blocks
In addition to elements printed onsite, we also designed a planter type made from small blocks. At the factory in Toyama, we printed 45 uniquely shaped blocks and manually stacked them onsite.
Only some blocks were filled internally with a magnesium oxide-based hardener. Bamboo rods were inserted in place of rebar as vertical reinforcement to improve structural integrity and cohesion.
4. Hand Wash Basin
The washbasins for users of the toilets were also 3D-printed at the factory and transported to the site. These cylindrical elements featured a recessed front for knee space and a maintenance opening on the rear, allowing them to be slid into position beneath pre-installed sinks and countertops.

Expo 2025 in Osaka serves not only as a showcase for the world’s most advanced technologies and visions of future society, but also as a large-scale experimental platform. Through this project, we aim to present a glimpse of a future society in which humans, nature, and machines coexist—realized through architecture built with natural materials like earth and advanced robotics.