Abstract: A solid imaging apparatus is provided that includes a replaceable cartridge containing a source of build material and an extendable and retractable flexible transport film for transporting the build material layer-by-layer from the cartridge to the surface of a build in an image plane. An operator using the device needs merely to remove a spent cartridge and replace it with a fresh cartridge to continue solid imaging virtually uninterrupted. The apparatus also includes the capability of withdrawing and inserting an imager without the operator having to perform a separate alignment step. A brush attached to the transport film and forming part of the cartridge provides for intra-layer removal of excess uncured build material. If desired, the apparatus can produce a fully reacted build. A high intensity UV source cures the build between layers. An injection molded build pad is designed to hold a build in an inverted position for improving the build.