1. A computer-implemented method of manufacturing 3D objects, including: a) processing circuitry at a server retrieving, from a database, a source model comprising a shell portion and an internal components portion for a 3D object and a plurality of defined control points relating to aspects of the shell portion for the 3D object, wherein the shell portion comprises a low resolution exterior surface mesh including a series of interconnected polygons with the control points relating to vertices of the exterior surface mesh and the internal components portion comprises at least one high resolution mesh having a higher polygon count than the low resolution exterior surface mesh; b) transmitting the low resolution exterior surface mesh of the shell portion and the control points relating to aspects of the shell portion from the server to a user device; c) displaying a representation model of the received low resolution exterior surface mesh on a display associated with the user device; d) receiving, via a graphical user interface provided on the user device, user specified modifications to at least some of the control points, wherein the user specified modifications are correlated to one or more selected predefined options; e) transmitting the modifications from the user device to the server; f) processing circuitry at the server receiving the modifications from the user device; g) processing circuitry at the server applying the received modifications to the source model to create a modified model; h) processing circuitry at the server subdividing a surface of the modified model to create a high resolution model; i) processing circuitry at the server modifying the high resolution model by combining it with the internal components portion of the source model, wherein modifying the high resolution model by combining with the internal components portion of the source model includes modifying positioning of the internal components portion in accordance with the received modifications to the control points and based on internal components portion constraint data included in the source model using metadata attached to specific features of the source model; and j) processing circuitry at the server generating print instructions based on the modified high resolution model for manufacture of a customised version of the 3D object.