The Voxel Quarantine Cabin, located in Collserola natural park near Barcelona, Spain, is a 12-square-meter off-grid prototype designed and built in 2020 by students and researchers from IAAC's MAEBB program. The Voxel is a self-sufficient cabin for one person to quarantine for 14 days. It embodies a "circular metabolism" by using locally sourced and processed natural materials with industrialized techniques to promote sustainable green building. All timber for the project came from Aleppo Pine trees harvested locally according to a sustainable forestry plan. This timber was milled, dried, processed, and pressed on-site into cross-laminated timber (CLT) panels for the structure. The 3.6 x 3.6-meter cube is assembled using metal-free lap joints and wooden dowels instead of metal fixings. The interior features exposed CLT, with the same wood used for custom furniture like a platform bed and desk. The exterior is insulated with cork and covered with a unique rainscreen made from offcuts of the CLT production. These charred wood slats, treated with the shou sugi ban technique for weatherproofing, are arranged in a gradient, highlighting the natural shape of the tree. Some sections of the façade are extended to house utilities like water tanks and an outdoor shower. The cabin is self-sufficient with a water-energy-waste system that includes solar panels and battery storage, rainwater harvesting and greywater recycling, and a biogas system for blackwater treatment to produce fuel and fertilizer. The roof also incorporates computer-designed garden boxes for local plants that help filter rainwater. photography by José Hevia.