3D printing of microwave absorbers gave rise to new shape optimization possibilities. However, new printable materials dedicated to this application have to be developed. In this study, an iron flake polymer composites was elaborated and characterized. Scanning Electron Microscopy observations demonstrated that iron flakes particles are naturally aligned along the extrusion flow direction without applied magnetic field during the 3D printing process. Magnetic anisotropy was demonstrated with both Vibrational Sample Magnetometer and microwave measurements. Indeed, at 5.4 GHz, a ratio of 1.71 between parallel and perpendicular susceptibility was demonstrated. These measurements demonstrated a self-induced magnetic anisotropy that can be used to control the angular robustness of free-space microwave absorbers.