Triply Periodic Minimal Surfaces (TPMS) are relevant structures for building synthetic bone grafts due to their tortuosity and their interconnected pores. In order to investigate their porosity and mechanical properties, three different hydroxyapatite-based TPMS were printed: Schwartz diamond, Schwartz primitive and Gyroids. Each structure was designed with three levels of porosity, two different pore sizes and two different wall thicknesses to understand the effect of pore size and wall thickness on the mechanical properties. The results highlight the importance of cleaning in the manufacturing process and its impact on the final porosity, especially for small pore sizes. Bending and macro spherical indentation resistance tests showed differences in the mechanical properties between the different structures, with a strong sensitivity of bending strength on the presence of cracks after thermal treatment. Notably, increasing the wall thickness is shown to increase the risk of damage in the solid part of the scaffolds, therefore lowering the bending strength.