You could kill a frog if you print a frog. Such is the conundrum of 3D printing, as some of the more commonly used printing materials are aquatically toxic if poured down the drain.
Once we can push a button to print stuff in our kitchens, it seems it will be a more sustainable way of manufacturing. Yet although it is astonishingly easy to make something in the shape of a toy or utensil, it doesn't guarantee it is safe enough for a child to put it in its mouth.
Regardless whether it takes place in our kitchens, there is no doubt we would be better off with manufacturing that is safer for life. And while additive manufacturing aka 3D printing shows great potential for being a sustainability killer app in terms of reduced waste, weight and transportation energy (by printing locally), it has a long way to go to truly deliver the green goods.