**1. Introduction**

The Design and Digital Manufacturing Laboratory of the University of La Laguna (Fab Lab ULL) has worked in the digital fabrication of a full-scale high-detail model (HDM) of the spatial instrument of the European Space Agency, named the Solar Orbiter mission Polarimetric and Helioseismic Imager (SO/PHI) [1]. This sort of physical replica entails deep information, which is essential for the preservation and transfer of aerospace heritage since projects launched into space are normally designed in order to not return to Earth.

The manufacturing of the HDM of the SO/PHI instrument was carried out under an approach that combined digital manufacturing techniques (low cost 3D printers, a CNC milling machine, and a laser cutting machine) and the use of a 3D computer-aided collaborative modeling software. The aim of this paper is to provide stages in the graphic engineering procedure for the digital fabrication of challenging projects, which require high detail through the resolution of a case study: the manufacture of a full-scale HDM of the spatial instrument PHI for the Solar Orbiter mission of the European Space Agency.

Rapid prototyping has made it possible to print 3D physical prototypes from CAD files [2]. However, this process is not always fast (since the model is not a single piece, and the printing process is not instantaneous). This lack of immediacy is plausible in architecture environments, where reduced scale models are indispensable and geometric simplification processes are required since buildings cannot be uniformly scaled [3].

3D digital printing precision and other fabrication variabilities have been a focus of interest in the scientific literature, including studies that compare the difference between the CAD model and the physical model [4]. In addition, other issues have dealt with the use of different digital manufacturing techniques with materials such as concrete [5] or the study of numerical models to analyze the behavior of timber folded surface structures using semi-rigid multiple tab and slot joints [6].

Nevertheless, there are many other challenges [7] when we face manufacturing a full-scale HDM of an engineering project. Although details are easily achieved in digital modeling, physical models provide important additional information for the conservation of engineering heritage, such as SO/PHI. Therefore, this article proposes a procedure to recreate engineering projects without the need for geometric simplifications through the use of low-cost digital fabrication methods.
