An experimental study has been carried out to investigate the material and stability performance of WAAM 316L stainless steel plates supported along both edges. The experiments were facilitated by testing a series of square hollow section (SHS) stub columns and tensile coupons extracted from the plates manufactured along with the stub columns. The tensile test results provided the material properties to be used for later analysis of the stub column tests, and indicated anisotropic material behaviour while displaying satisfactory material ductility. The SHS stub column dimensions fall in the range of ‘slender’ cross-sections as defined by Eurocode 3. Their geometric profiles were 3D laser scanned and analysed prior to the compression tests. The failure modes and load carrying capacities of the WAAM SHS stub columns were analysed and compared to the specimens in previous similar studies. The use of the Effective Width Equation in Eurocode 3 and the Continuous Strength Method for the design of slender WAAM stainless steel plates are evaluated.