sPHENIX plans to build a world class jet detector at RHIC. Previously inaccessible measurements include jets reconstructed with hadronic calorimeters and fully resolved upsilon states. The current plan includes a highly granular silicon pixel detector (MAPS), a silicon strip detector (INTT) and a time projection chamber (TPC). The tracking system will work in continuous read out, at high data collection rates -15kHz- and will be able to provide momentum resolution. In this poster we present the RND work done towards the mechanical design and construction of the outer field cage of the TPC.