New Balance’s Latest Shoes Come With 3D-Printed Soles

If you currently own a pair of running shoes, the odds are that the midsole—the shock-absorbing layer in between the inner and outer soles—is made from molded ethylene vinyl acetate (EVA), which is squishy, resilient foam. As a cushioning material, EVA foam isn’t bad. It’s elastic, affordable, and can be dyed a variety of colors. But an EVA midsole offers the same degree of support throughout the shoe, and what you really want is different levels of support across different parts of the foot. Also, EVA breaks down and compresses with repeated use, and this degradation is the reason many runners replace their shoes every few hundred miles. For these reasons, shoe companies have been actively experimenting with materials to …