###### Abstract
Even though coarser particles can be associated with better flowability, a wider, bimodal PSD type results in a faster flowing of the powder particles, improving the packing density [23]. Furthermore, a narrow PSD with a high void ratio will increase the permeability in the horizontal directions, and a higher mean diameter of the powder particles increases the vertical permeability [24]. For the iro3d SPD, better flowability should be prioritized [25], taking into consideration that powders' chemical compositions will greatly affect the printed parts [26]. Regarding the chemical properties of the support powder, both regular sand and silica sand can be used as the support material. Both sand types have melting points above 1500 \({}^{\circ}\)C, which is higher than the reported values for glass sintering that start at around 650 \({}^{\circ}\)C [27]. Even so, 5% to 20% of regular or brown sand are impurities such as iron, carbonate, and potassium, which make some sand types chemically reactive, possibly damaging the crucible or glass when fired up. To produce metal parts with the iro3d, a powder runner is usually built on top of the part. Inside the furnace, this runner allows the infill metal to flow through it, soaking the remaining metal powder once the infill material melting temperature is achieved [16]. Figure 1: The iro3d selective powder deposition (SPD) process. (**A**) Iro3d model C machine with main components identified. (**B**) Section view scheme of the crucible with support and build powders inside, after the deposition stage and before sintering. (**C**) Example of a power depositing glass powders inside an alumina crucible. Concerning glass powders, the manufacturing workflow used to produce specimens in this research did not include the building of a runner during deposition or the use of infill material in the sintering stage. The scheme of Figure 1B demonstrates the result of a build, after the layer-by-layer process of selectively pouring glass and support powders into a crucible. Figure 1C is meant to demonstrate the deposition stage where, within each layer, the head system exchanged its tooltip between the four available pourers. During the powder deposition stage of the iro3d, the particles are distinguished by their mean diameters, being divided into two different categories, fine and rough sizes. Fine powders were employed in the border between build and support materials, as exemplified in the scheme of Figure 1B, promoting the reduction of surface roughness. Considering the poorer's diameter, the build and support powders' PSDs should be roughly 1/10 of the poorer diameter, between 40-90 \(\upmu\)m and 90-190 \(\upmu\)m for fine and rough powders, respectively [16], which is in line with the work performed by [PERSON] [28] that recommends powders to be five to 10 times smaller than the given outlet diameter. Regarding the iro3d SPD classification within AM process families [29], the two closest standardized AM categories are powder bed fusion and binder jetting [30]. Even so, SPD does not use a binder in each deposited layer of powders, and its temperature inside the furnace does not reach the melting temperature of the build powder [31]. For this reason, SPD could be better defined as a bottom-up layered technique that selectively deposits small discrete particles using a single channel [32], or be understood as an indirect powder bed process that uses a thermal source as a post-processing stage to cast or sinter the final part [33]. This research aimed to evaluate the adequacy of the iro3d SPD process in the production of glass-based products. To do so, several cuboid specimens were produced under variable powder deposition and sintering strategies. Several studies have focused on evaluating glass sintering stages, namely, the effect of powder composition and the temperatures involved. [PERSON] et al.