This book presents the experimental tests and material examinations of the innovative ECOCELL and BAMBOOCELL lightweight composite construction technology developed by architect, entrepreneur, and inventor Fredy Iseli. Over a period of more than thirty years of development, a new construction system based on honeycomb composite structures made from paper, wood, and bamboo has been created. The aim of this technology is to significantly reduce the consumption of raw materials, lower construction costs, and provide environmentally sustainable building solutions. Between 2013 and 2021, extensive laboratory tests and structural examinations were carried out to evaluate the performance of these materials and construction elements. The tests included investigations into compressive strength, bending strength, fire resistance, thermal insulation, shear strength, and acoustic performance. The results demonstrate that honeycomb composite structures can achieve high structural stability while using a large proportion of renewable and recycled materials. This publication documents these tests, material studies, and technical developments in detail. It provides engineers, architects, researchers, and interested readers with insight into the technical foundations of the ECOCELL and BAMBOOCELL building systems. By publishing these results, the author aims to preserve the knowledge and development work behind this technology and make it accessible for future research and potential industrial application in sustainable construction.