This chapter sheds light on the vital world of protein biogenesis, folding, and misfolding, processes at the heart of cellular life. Proteins, the molecular machines of life, must fold precisely into three-dimensional structures in order to function. Missteps in this delicate choreography can lead to severe diseases such as Alzheimer’s, Parkinson’s, or cystic fibrosis. Cells deploy sophisticated quality-control systems, chaperones, and degradation pathways to manage this complexity. Yet, environmental stress, mutations, or aging, can overwhelm these safeguards. Membrane proteins, in particular, pose unique challenges: they comprise nearly a third of human proteins and serve as critical receptors and transporters, yet their complexity renders lab study difficult. Investigating how these proteins fold, insert into membranes, and sometimes misfold, is essential for understanding disease mechanisms and advancing drug development and synthetic biology. In our laboratory, we study these systems using custom-built magnetic tweezers to measure forces at the pico-Newton scale. This requires a completely multidisciplinary expertise, covering large facets of science: optics, engineering, biochemistry, and computer science. We describe here the experimental design, noise-suppression strategies, and high-resolution, high-frequency measurements that we can perform on proteins. Through meticulous instrumentation and data analysis, we reveal detailed folding pathways and dynamic intermediates, demonstrating how state-of-the-art single-molecule techniques unlock new insights into protein behavior, with profound implications for new therapies and biotechnology.