By Evan GarciaGEORGETOWN, Texas (Reuters) - As with any desktop 3D printer, the Vulcan printer pipes layer by layer to build an object – except this printer is more than 45 feet (13.7 m) wide, weighs 4.75 tons and prints residential homes.This summer, the robotic printer from ICON is finishing the last few of 100 3D-printed houses in Wolf Ranch, a community in Georgetown, Texas, about 30 miles from Austin.ICON began printing the walls of what it says is the world's largest 3D-printed community i...