The article is set within the experiences of Cagliari's DICAAR on the sustainable recovery of Sardinia's inland areas and deals with the definition of guidelines for the design and construction of a prototype for multifunctional spaces in rural area. The site chosen for the realization of the prototype is in the locality of Fustiolau, a disused quarry at the center of a process of landscape reintegration, in the historic region of Marmilla. In this specific case, the rural-kit project is aimed at accompanying agro-services, configuring itself as a didactic-experimental building for visiting the area's archaeological sites and for environmental education. The spatial articulation of the device is simple, a barycentric classroom intended to accommodate the primary uses, to which are juxtaposed, along the perimeter, accessory spaces obtained with prefabricated cells in the form of flexible plug-ins, which can be integrated with a variable distribution arrangement. The construction principles of the device are the repeatability of the module, the possibility of disassembly of the construction elements, dry construction, recycling of raw materials, and, above all, the reuse of the constituent elements and the possibility of integral reversibility. From these assumptions, the project is distinguished by simple building elements: the basement that manages the relationship with the ground; plug-ins, load-bearing cells made of recy-cled concrete, which form the building's load-bearing structure and define its metrics; the roof made of glulam and solid wood panels and covered with a metal sheet, a device for microclimatic regulation and renewable energy production. Digitization, sensing and advanced control will enable monitoring of the prototype's environ-mental performance for a multi-year duration during ordinary use to assess its efficiency and degree of overall sustainability.