Multi-material, multi-technology fabrication systems provide opportunities for unprecedented design freedom, increased manufacturing efficiency and additional in-line functionality. We demonstrate a novel, modular hybrid additive manufacturing (hybrid-AM) framework, comprised of up to 9 complementing, interchangeable functional modules (e.g. fabrication and characterization). The inherent flexibility of the hybrid-AM process provided an opportunity to address conventional manufacturing limitations including time-consuming, multi-step assembly and restrictions on geometric form factors. Functioning, free-form energy storage devices (supercapacitors, EDLC’s) were manufactured in a single, multi-material operation. Furthermore, an integrated dielectric surface mapping technique has been demonstrated for the non-destructive, real-time reconstruction of the 3D dielectric permittivity distribution within functional devices (RF optics) throughout build. The finite volume method provided a form of in-line quality control. A bespoke, modular printing host (GUI) was developed to, among other things, control the hybrid-AM machine, interface with 3rd party scientific equipment, as well as log and analyse production/characterisation data in real-time.