PAUL HSIEH IN FORBES: Why 3D-Printed Untraceable Guns Could Be Good For America. “Current law already allows home hobbyists to build their own firearms provided they are for personal use only (and not for sale). Such guns are already ‘untraceable.’ 3D-printing doesn’t change that basic fact — it merely allows a wider range of hobbyists without specialized machine shop skills to do what’s already legal.”