The preservation and restoration of intricate stucco ornaments, which are part of our collect cultural Heritage, is under threat due to a diminishing number of skilled restoration plasterers. The highly physically demanding- and labour intensive nature of this work makes it unsustainable for the human body and advocates for a more sustainable alternative restoration method for the future. Digital Fabrication has the potential to offer such an alternative method. While 3D scanning, digital repair and 3D printing are all proven technologies, stucco ornament restoration often requires an on site fabrication solution directly onto a ceiling or wall due to the brittle nature of prefab stucco elements. The research explores how an in-situ 3D printing technique can be developed for the restoration of stucco ornaments by focussing on three main topics: 1) developing gypsum-based 3D printing materials, which are compatible to gypsum ceilings and comply with criteria for extrusion based 3D printing; 2) Designing and prototyping 3D printing tools including an extruder and material delivery system; 3) Conceptualizing a Restoration Robot Platform with which the developed printing material can be used with the developed 3D printing tools, for on site stucco ornament restoration. The insights gained from the development of the printing material and printing process are integrated into digital fabrication software used in practise, through a proposed plug-in and workflow.