3DMatter decided to put some research into what effect infill percentage, patterns, and layer height have in terms of causing stress and breakage in 3D prints. They did have some surprises, mostly when considering 90% infill where they deduced that air voids are created, causing structural faults which result in stress but lower elongation in breakage. While discovering that linear and diagonal patterns have the best results, there was little difference in the end between those or hexagonal. They also pointed out, quite predictably, issues tend to arise on the the Z-axis due to weaker layers. More details on the findings by 3DMatter can be found here: http://3dprint.com/51065/infill-perc...s-3d-printing/