You may have noticed my complete lack of posting about Cody Wilson and his printed gun technology. The reason for that is simple: it’s a gimmick. Sure, printed guns can work, but the question is inevitably “how long?” When it comes to the catastrophic failure of the thermoplastics used in the construction of the barrels and firing chambers, it isn’t a matter of “if,” but “when.” As a practical matter, with current and near-term technologies, plastic guns are a loser.That said, some of the emerging technologies that make plastic guns feasible are viable for metalwork as well, and machines like...