Online shopping giant Amazon proposes to use 3D printers mounted on vehicles to print customer purchases on the fly and deliver them immediately. Because of the overlap between production and transportation processes, such a mobile manufacturing mode offers potential savings in lead times and inventory costs. However, the decisions associated with the two processes are intertwined, making it challenging to achieve satisfactory machine schedules and vehicle routes. To address the situation and fully understand the benefits of the mode, we study a related optimisation problem of finding routes for vehicles and production schedules for 3D printers mounted on them with minimum travel costs. First, we construct a mixed-integer programming model to formulate the problem. Then, we develop an exact algorithm to solve it. Specifically, we propose two propositions about the optimal production schedule of machines in the route and develop a labelling algorithm for the pricing problem. And we devise a problem-specific heuristic labelling algorithm to speed up column generation. We use two sizes of instances with five problem parameter settings (including 290 instances) to validate the effectiveness of the algorithm. In addition, we provide some managerial insights for decision-makers by comparing the novel mode with the traditional manufacturing mode.