When a soft material is molded into a shape with sharp corners, its surface stress drives deformation rounding it off.  This demonstrates the existence and action of surface stress in solids and also how it can be measured.

Paretkar, Dadhichi, Xuejuan Xu, Chung-Yuen Hui, and Anand Jagota. “Flattening of a patterned compliant solid by surface stress.” Soft matter 10, no. 23 (2014): 4084-4090.

Jagota, Anand, Dadhichi Paretkar, and Animangsu Ghatak. “Surface-tension-induced flattening of a nearly plane elastic solid.” Physical Review E 85, no. 5 (2012): 051602.