<p>Direct programming of shape memory polymers produced via extrusion-based additive manufacturing (EBAM), a.k.a. fused deposition modeling (FDM), has emerged as an attractive 4D printing method for creating functional engineering constructs. The underlying principle behind this is the generation and the control of residual stress during the printing process, which serves as the driving force for triggering shape-morphing mechanisms. These structures are used in various critical engineering applications ranging from deployable space structures to biomedical devices. This work investigated the effect of printing parameters, including nozzle temperature, layer thickness, printing speed, infill percentage, and bed temperature, on the longitudinal shrinkage of flat structures fabricated with polyurethane-based shape memory polymer (SMPU). Factor screening analysis and a subsequent full factorial design with three levels were employed to obtain a regression model to control and predict the amount of shrinkage in planar structures, commonly used as a building block to create different actuation mechanisms like bending, twisting, or folding. Additionally, the effect of the infill pattern and sample thickness is investigated. The results showed that nozzle temperature, printing speed, and layer thickness are the most significant factors controlling shrinkage deformation. Furthermore, the infill pattern significantly influences the directionality and the magnitude of strain after the recovery stage. It was also found that sample thickness is inversely related to shrinkage deformation.</p>