This book focuses on the possibilities available for improving the mechanical properties and geometric accuracy of selective laser sintered parts produced from non- commercial polyamide 12 composites. The specific material of interest is PA 12 filled with glass beads. This work describes a study of the relationship between filler particles, the polymer matrix and processing parameters and their influence on the mechanical properties and geometric accuracy of the composites. The aim of the study is to better understand the effect of coupling agents on the above mentioned properties. The experimental techniques implemented in this work are readily transferable to virtually any material system used in Additive manufacturing. The continuation of this experimental work by other researchers, institutions and industries directly concerned will be beneficial for materials improvement or development and accuracy characterisation in Additive manufacturing techniques.