Parts made using the FFM (FDM) process are stronger in some directions than in others. This is due to imperfect adhesion between printed layers. This directional or anisotropic structural strength is a significant limiting factor for the structural integrity of 3d printed parts made with the common FFM process.A method to drastically reduce this effect is described in an expired Stratasys patent, US1997/5653925A. As of this writing, I have not seen this feature implemented in any of the common ...