3D Printing has significantly lowered the barrier-of-entry in terms of cost, time and accessibility to micro-fabricated intricate shapes and sophisticated devices, in various fundamental research domains. 3D printers can manufacture objects with sizes ranging from few microns with two-photon stereolithography (TPS) to centimeter. In the field of microfluidics, the more "user-friendly" implementation and the easiness of 3D printing of complex structures digitally designed (3D CAD) compete the robust but heavy implementation of soft lithography. 3D printing allows direct and rapid fabrication of microfluidic chips. Among all 3D printing technologies, 3D printings based on stereolithography have attracted particular attention since sub-100 µm internal channel diameter has recently been demonstrated. In this context, polymers are strategic materials. However, the main limitation relies on the fact that the properties of the chosen monomer impose the surface chemistry of the envisioned object. At technological level, substantial efforts have been devoted to improving writing devices (writing resolution and speed). However, little attention has been given to increasing the chemical diversity or surface functionalization of the written scaffolds. Today, it is not yet possible to modify the surface chemistry in a simple way from 3D printers other than robust but heavy and/or cumbersome post physical or chemical treatments. So mechanically compliant and chemically functionalized surfaces (polarity, texturing, biocompatibility, etc…) are still untenable. Moreover, it is a hard puzzle to solve when surface modifications are to be done at located place (patterning). 3D-CustomSurf project aims at developing new photo-initiator with advanced properties and new methodologies in additive manufacturing techniques 3DP-UV (mm to cm scale) and TPS (µm scale). Our strategy is grounded on the use of photo-Reversible-Deactivation Radical Polymerization (photo-RDRP) techniques adapted to the specific conditions of 3D manufacturing by photo-polymerization applied to microfluidics field where this will be an asset when specific patterning is needed. Indeed, surface modification of internal channels of a microfluidic device is still limited by multi-steps process. Our strategy is grounded on i) the design and synthesis of unique photo-sensitive alkoxyamines containing specific chromophores for both 3DP-UV and TPS and the initiating moiety ii) a careful examination of their photo-physical and chemical properties iii) a thorough investigations of their efficiencies for first and re-polymerization (living polymerization) under laser writing (3DP-UV, TPS) iv) methodological investigations for first polymerization (3DP-UV) followed by inner surface functionalization (chemical and patterning) by TPS on simple prototypes (tubes) v) the fabrication of a microfluidic device with customized inner surface channels for double emulsion preparation. Coupling laser writing with RDRP methodologies is a novel approach which has been poorly investigated notably in the field of TPS where no work has been reported with a such combination. Novelty and especially lack of thorough investigations about chemical and physical phenomena involved during the 3D fabrication process explain the absence of such approach in 3D laser printing area. Our strategy is expected to be a breakthrough in this field since NMP2 coupled with 3D Printing allow to consider the object on the one hand and its surface modification (chemistry and structuration) on the other hand in a protocol of great simplicity.