<p>This work presents a finite-element (FE) framework for predicting the mechanical response of polymeric powders subjected to confined compaction. A contact-based FE formulation captures the deformation of individual microspheres, their evolving contact network, and the accompanying reduction in bulk porosity inside the mold. Two nonlinear constitutive descriptions, namely, an elastoplastic model with multilinear hardening and a Perzyna-type viscoplastic model, are implemented to assess both rate-independent and rate-dependent particle behavior. Representative-volume simulations of an epoxy-resin powder are carried out under multiple loading-unloading cycles to quantify how the mold-constrained effective Young’s modulus and porosity evolve with the compaction history. Because this effective modulus reflects both the intrinsic particle stiffness and the increasing confinement and densification of the packing, it can exceed the single-particle modulus as the contact network develops. The results show that the cumulative loading history, number of cycles, peak pressure, and loading rate, strongly influences densification and the apparent macroscopic stiffness of the compact. By providing a predictive tool for effective property estimation without costly trial manufacturing, the proposed approach can guide optimization of compression-molding parameters for polymer-based composites and other powder-processed components.</p>