## 3 Materials and Methods
### Materials  
The virtual models of the products evaluated were generated with the computer-aided design program Solidworks(r) (2019 version, Dassault Systemes SE, Velizy-Villacoublay, France), commonly used by industrial designers, and the virtual models were generated using the AR program Unity(r) (12 October 2017, 2.0f3 version, Unity Technologies, San Francisco, CA, USA). This software was selected because it represents the virtual perspective of a high-quality object, provides fluid movement and rendering allows for a clear appreciation of changes in the plane of the containers studied. The engine of the AR software used was Vuforia(r) Engine 8.3, which uses deep learning to generate the graphic models instantly. In order to associate the CAD models in AR with the samples, each of the products was associated with a QR code with the minimum size to be read by the application: \(47\times 47\) mm. It should be added that the combination of the CAD model, the sample and the QR code result in the HHP. Physical finishing samples have been developed in this experiment using additive manufacturing and thermoforming techniques. Afterwards they were attached to a support, which includes the QR code, to allow manipulation of the samples while evaluating the virtual image. Also, although the AR program allows use of any digital device, we have worked with a 10.1 inch Samsung(r) Tab A 2016 Tablet with an IPS display with a maximum resolution of 1920 \(\times\) 1200 was used to improve the functionality of the procedure. In addition, four types of packaging have been created for the purpose of carrying out the experiment, which, in turn, includes four different reliefs. Figure 3 shows the geometries used, where the model type A presents relief in the form of sawtooth, type B a dot pattern, type C ribs and type D undulations. Figure 4 shows a comparative example of visualization of the physical and virtual product. The physical prototype, Figure 4a, has a transparent finish and the virtual prototype has a white finish, Figure 4b, showing in the image the superposition of the prototype in AR over the physical prototype. For the physical samples, the moulds of the containers were constructed by means of additive manufacturing (FFF) on a Zortrax M200 printer. They were printed using a layer height of 0.2 mm, filling density of 15% and wall of 1.4 mm to prevent the surface roughness caused by the layer manufacturing of the FFF from being transmitted to the thermoformed sheet, in accordance with [42]. Hence, users were only able to perceive the designed reliefs. The containers were then manufactured using a Formech 450 DT thermoforming machine with a 500 \(\upmu\)m thick transparent PET sheet. This material allows the containers to be transparent and the colour does not distract the interviewees. Figure 4: Images of the experiment: (**a**) Image of the real packaging and (**b**) packaging in augmented reality (AR) superimposed with the real one. Figure 3: Design of moulds for thermoforming. (**a**) Model A mould with sawtooth relief; (**b**) Model B mould with relief formed by a dot pattern; (**c**) Model C mould with ribs; (**d**) Model D mould with undulating relief. Figure 5 shows the three physical products evaluated and the three QR-coded flat relief samples used to generate HHP by using AR. Thus, the coding of the relief samples, with associated QR code, is the same as the container to which the sample corresponds and the termination AR has been added. In order to carry out the experiment, 6 samples were manufactured, Figure 5: two samples of the type A and B container models and one sample for types C and D (Figure 3). This is due to the fact that the prototypes type A and B were evaluated by means of the conventional experimental physical prototype and by means of the HHP method proposed in this work.