No-one's mentioned that 3D printed items do not possess the same physical properties as conventionally manufactured items via processes such as blow-moulding, injection moulding, from-solid machining,etc. Anecdotal evidence suggests that a 3D printed item will have at best only 60% the strength and reliability of, say, an injection moulded article. Obviously this percentage can drop even further under certain dimensional constraints i.e thin-walls, non-solid infill, etc and also under procedural conditions i.e. unfavourable extruder temperature resulting in delamination.