Charles R. Goulding and Kellen Coleman drill into how the ongoing U.S. Steel acquisition battle could redefine material availability, costs, and innovation in the fast-growing 3D printing industry.

This week’s question is about an old 3D scanner, the Eora. Reader Leo asks: “Some years ago I purchased an Eora 3D scanner for use with my iPhone. For a while it worked well, but with a change of ...