Developing shape-changing systems is challenging, and origami offers a unique approach by transforming 2D planes into 3D structures. While existing active reconfigurable origami systems enable functional changes - such as mechanical tuning, multi-modal locomotion, and adaptive structures - they often suffer from slow actuation, complex control, or large unit sizes. We present a compact, modular shape-changing system composed of origami pop-up cells that transition between a cubic block and a flat sheet. Magnetic connections enable easy assembly, rearrangement, and repair, ensuring robust actuation. A single 30 mm, 2.2 g cell transforms within seconds. Demonstrations include a 4 × 4 matrix and a 5 × 3 tangible letter-shifting display, showcasing the system's potential for physical shape-shifting applications.