Throughout history, cultural heritage has accumulated, and is often embodied in monuments, structures, and notable figures. Cultural heritage preservation and management also include digitalization, allowing tangible monuments to be managed as digital inventory with “digital twins”. This provides innovative ways to experience and interact with the real world, in particular by using modern mobile devices. The digitalization of monuments opens new ways to produce decorative items based on the shape of the monuments. Usually, decorative items are produced by craft businesses, family-run for generations, with specialized skills in metal and stone processing. We developed and tested a methodological proposal for frugal innovation: how to produce decorative items with minimal costs based on digital twins, which are particularly in demand in tourism-driven countries like Croatia. A micro-business with three employees, specializing in “metal art,” aims to innovate and expand by producing small-scale replicas of cultural heritage objects, such as busts, statues, monuments, or profiles. A method has been developed to create replicas in the desired material and at a desired scale, faithfully reproducing the original—whether based on a physical object, 3D model, or photograph. The results demonstrate that this sustainable frugal innovation can be successfully implemented using affordable tools and licenses.

The main aim of this research was to investigate the aluminum AlSi9Cu3(Fe) machining chips recycling possibility utilizing a direct hot extrusion process and thixoforming. The thixo feedstock was prepared directly from the aluminum alloy AlSi9Cu3(Fe) machining chips waste without any remelting step. The machining chips were compacted, and direct hot extruded to create the solid samples and thixo feedstock. The aluminum alloy AlSi9Cu3(Fe) machining chips had a high degree of plastic deformation and after extrusion and heating in the semisolid temperature range, the suitable globular microstructure was achieved, which is a precondition for a successful thixoforming process. This approach can be characterized as a semisolid recycling process with a lower energy consumption, a higher material yield, and reduced greenhouse gas emissions into the atmosphere compared with conventional casting and recycling. Optical metallography, scanning electron microscopy accompanied with energy dispersive spectroscopy, electrical conductivity, and mechanical properties investigation were performed on the reference casted sample with a dendritic microstructure, the extruded sample with a severely deformed microstructure, and finally the thixoformed samples with a globular microstructure produced with different parameters, according to the Taguchi L4 (2³) experimental plan.

The main aim of this research is to investigate the possibilities and challenges involved in the electric arc welding of solid-state-recycled EN AW 6082 aluminum alloy. Lately, solid-state recycling has gained increased attention as a more sustainable and efficient aluminum recycling method, whereby only about 30% of the energy of conventional recycling is used. This method is based on the deformation of small-sized metal waste into solid recycled specimens without a remelting step. For the welding of solid-state-recycled specimens, both metal inert gas welding and tungsten inert gas welding methods are used. To evaluate the weldability of solid-state-recycled material, welded specimens are compared with welded, commercially produced EN AW 6082 aluminum alloy sheets. The welding is performed using the same processes, parameters, and conditions. To evaluate the welding potential of solid-state-recycled alloy, tensile tests, microhardness tests, optical metallography, and scanning electron microscopy, accompanied by energy-dispersive spectroscopy analysis, are performed.