## 1 Introduction  
Additive Manufacturing (AM) has proved to be a great technology for manufacturing 3D objects that can serve many purposes such as prototypes, fully functional parts, educational tools, or tools that facilitate other types of manufacturing technologies. In particular, AM has been significantly developed to be implemented in the investment casting (IC) industry during the last decades. When AM is used to produce the patterns for metal casting, the manufacturing process is referred to as rapid investment casting or RIC. [PERSON] et al. [1] mentioned eight types of commercially available AM technologies that are used to produce either wax or non-wax patterns for IC. Among those methods, FDM technology is of particular interest for it is a low-cost and widely available method. Additional advantages include the larger build plate and simplicity of the manufacturing process. During the manufacturing process, a wire of plastic/filament is melted and immediately deposited on a flat platform, creating a cross-sectional feature of an intended object. The process is continuously repeated, and layers build upon layers, creating a solid object. The capabilities of FDM technology to produce IC patterns have been studied extensively. Different materials, such as general plastics and wax-based filaments, are available in the market to be used as patterns for RIC. Among non-wax materials, the acrylonitrile butadiene styrene (ABS) showed better performance due to a superior surface finish compared to wax filament [2]. The advantage of using non-wax material is in the superior mechanical properties that prevent the pattern from failing during handling or transportation [3, 4]. Nevertheless, several downsides have been identified when using non-wax Rapid Prototyping (RP) patterns. They include large thermal expansion during pattern burnout, leading to ceramic shell cracking, and a higher amount of residual ash [5, 6, 7, 8]. Moreover, the gases generated from burning non-wax patterns significantly contaminate the mold material, which in turn affects the casting quality. As far as the critical pattern burnout temperature is concerned, when using non-wax patterns, the ceramic shell cracking occurs when the pattern reaches its glass transition temperature (Tg), according to [PERSON] et al. [6]. For ABS,the Tg is around 100 \({}^{\circ}\)C [9; 10] with a melting temperature (Tm) ranging from 200 to 240 \({}^{\circ}\)C. From the physical properties of the ABS filament, it is evident that the burnout procedure is the only proper means of removing the pattern from the ceramic mold. In such a case, the material has a negative environmental effect due to wastage and high energy consumption. As for wax-based filaments, the first materials were developed in the 1990s by Stratasys and had the commercial names ICW04 and MW01. In 1994, [PERSON] et al. designed several experiments aiming to modify the composition of wax filaments by mixing wax-based materials ICW04 and MW01 with plastic formulations to improve physical and mechanical properties [11]. In addition, the authors briefly describe how the two factorial designs were implemented to analyze the effect of printing and envelope temperatures on the surface quality of manufactured parts. Although the study contains meaningful information on the material's properties, the study is void of important details on printability, dimensional accuracy, and surface roughness of parts made of castable wax. The other mention of wax-based FDM material can be found in the review work done by [PERSON] et al. in 2005 [4], where the wax filament was described as a material having inferior mechanical properties. Table 1 summarizes the recent works on the application of FDM technology in IC. Considering the current market, a list of commercially available \"made for casting\" filament products with some characteristics is shown in Table 2.  
To the authors' best knowledge, the reports on the effectiveness of the commercial FDM waves listed in Table 2 are unavailable, except for the MoldLay.