After spinal cord injury, electrical stimulation of the roots inside the spinal column at the level of the cauda equina is a safe and effective way to regain some degree of control over lower body function, e.g. bladder and bowel management and leg movement. The success of current systems used for so-called intrathecal stimulation is limited by the low number of stimulation channels, which are in consequence of the maximum acceptable number of transdural cables. In order to overcome this limitation, we developed an active electrode with integrated electronics, providing four individual stimulation channels that requires one cable only. This paper outlines the different elements of the so-called active book with the emphasis on its preliminary construction and assembly.