This project aimed to characterize and compare two vat photopolymerization (VPP) 3D printing technologies, low-force laser-cured (SLA) and cured using a liquid crystal display (LCD) (mSLA), using three commercially elastomeric resins. Since the invention of VPP in the 1980s, significant technological improvements have been made, although both SLA and MSLA suggest similar theoretical performance, prior practical experiences revealed differences in results, particularly when printing elastomers, known as soft resins. To address this, the study evaluated technology-dependent variations in mechanical and optical properties by analyzing parameters such as stress, fatigue, transparency, and surface roughness, as well as the relation between viscosity and printing temperature. The SLA printer operated automatically with predefined parameters matched to the resin, while the MSLA printer functioned in an open mode, requiring manual input of settings such as UV exposure time and printing speed. In this study, we optimized these parameters using Jacobs’ working curve, a reliable tool to determine optimal exposure times. Consistent trends were observed across all resins, confirming the applicability of Jacobs’ curve. Additionally, shrinkage was detected within the first 30 printed layers in MSLA; this was mitigated by proper orientation and supports of 25–30 layers. Scanning electron microscopy (SEM) was used to analyse surface morphology and layer structure, while mechanical characterization was performed by uniaxial tensile and fatigue tests. Overall, this work provides a systematic strategy for optimizing MSLA printing parameters and highlights how processing conditions affect the quality and mechanical performance of soft resins, offering practical guidelines for reliable and cost-effective fabrication.
