Slate production in Portugal generated from the extractive companies has remarkably increased, from 52 to 80 million tons from 2020 to 2021. Waste disposal has adverse environmental impacts, including soil degradation, water pollution, and increased landfill sites. This panorama reveals an opportunity to explore this industrial waste to develop new products, thus contributing to mitigating its negative environmental impact. This work aims to implement a practical strategy that outlines incorporating slate waste in developing earthenware-based materials for 3D extrusion. It was found that up to 70% of this waste can be incorporated into the composition of commercial white earthenware. The feasibility of adding other types of industrial waste, such as marble or granite dust and other non-mineral materials, was also demonstrated. The extrudability, buildability, and printability were evaluated in a manual extruder and a 3D printer (Delta WASP 40100). After extrusion, the samples were fired at temperatures ranging from 950 °C to 1180 °C in cycles of 16h, revealing similar shrinkage of the white earthenware and different colors. The product design sought to explore the potential of including slate on earthenware-based materials, from its traditional applications to its use in contemporary contexts of facades and building’s interior spaces, using 3D printing extrusion technology. This work not only reinvents slate as a sustainable material but also demonstrates the potential of 3D printing for design and environmental preservation.