Additive manufacturing technologies, commonly known as 3D printing, have gained widespread recognition in many areas of industry, research, and prototyping. One of the most widely used additive manufacturing methods is fused deposition modelling (FDM), which, owing to its simplicity, accessibility, and relatively low operating costs, is extensively used in industrial, educational, and hobbyist applications. Traditional methods for manufacturing transparent products, such as glassware and its substitutes, involve demanding processing conditions, limitations in shaping, and relatively high production costs. Because glass requires specialized thermal and mechanical processing, alternative methods are being explored to produce prototypes with a similar visual appearance using materials that are easier and more flexible to process. This study investigated the possibility of producing FDM-printed prototypes with a visual appearance sufficiently similar to glass for use in rapid prototyping. Three filament materials—PLA, PETG, and PCTG—were evaluated, and the influence of selected printing parameters was investigated using a design of experiments (DoE) approach. The study was designed to identify a low-cost, rapidly manufacturable, and potentially disposable prototype capable of providing a sufficiently glass-like visual impression for early-stage glassware and packaging design. In this industrial context, such prototypes are intended to support decisions concerning product shape and visual appearance and are ultimately evaluated visually by designers and production personnel. Therefore, the final specimens were assessed using a Visual Analogue Scale (VAS), with participants rating perceived transparency, colour similarity, gloss, and surface smoothness. Among the tested materials, PCTG received the highest mean ratings for perceived transparency (25.9 ± 15.8), colour similarity (39.0 ± 16.8), perceived gloss (48.7 ± 20.1), and perceived surface smoothness (32.7 ± 19.9) on a 100-point scale.