"Building the Yonah: A 3D Printed HO Engine" is 72 pages devoted to creating the Yonah, a participant in the Great Locomotive Chase that has never been available in HO Scale before. The bulk of the parts are 3D printed parts from Shapeways that were designed by Gerry Dykstra. The book contains complete bills of material, including current prices and vendors, as well as useful engine modeling tips that make the book worthwhile even for those deciding not to build the locomotive at this time. For example, it includes instructions on how to create ankle rails and how to assemble Gerry DykstraÕs new solderless driveshaft kits.