The respiratory system relies on mucus to trap and clear inhaled impurities, but diseases like cystic fibrosis or COPD can disrupt its rheological properties, leading to mucus plug formation and airway obstruction. In cylindrical airways, this process is driven by the Rayleigh-Plateau instability, where liquid bulges grow and coalesce, potentially damaging epithelial cells due to elevated wall shear stress. Numerical studies highlight the role of viscoelasticity in post-coalescence instability, introducing a secondary stress peak. This internship will experimentally investigate plug formation using artificial mucus in a cylindrical glass channel, employing high-speed imaging to correlate plug morphology with wall stress, aiming to understand its impact on epithelial cell damage.