3D printing technology, also known as Additive Manufacturing (AM), has revolutionized object prototyping, offering a simple, cost-effective, and efficient approach to creating structures with diverse spatial features. However, the mechanical properties of 3D-printed structures are highly dependent on the material type and manufacturing technique employed. In this study, ultrasonic testing methods were used to comprehensively characterize standard samples produced using two popular printing techniques: material extrusion and vat photopolymerization. The investigation focuses on seven commonly used 3D printing polymer materials, namely nylon, PET-G, flexible polymer, polycarbonate, acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), and photopolymer resin. Through ultrasonic testing, the mechanical parameters of objects made of different polymer materials were found. Some of these parameters are Young's modulus, shear modulus, acoustic impedance, and absorption. A comparative analysis of these parameters in different objects provides insights about their respective performance and behavior. This information may be useful to enhance the design and performance of ultrasonic lenses and lab-on-a-chip devices. Findings indicate that the vat photopolymerization printing process yields high-quality samples that exhibit minimal deviations in thickness, diameter, and surface parallelism. Moreover, microscopic analysis of the vat photopolymerization samples revealed low levels of porosity, which suggests that the material can be considered homogeneous. In contrast, the material extrusion samples showed significant porosity in the form of gaps between the deposited filaments, which had a direct impact on their mechanical and acoustic properties.