We prepare colloidal plasmonic nanoparticles of various sizes, shapes and spatial arrangements and study their plasmonic resonances, confined acoustic vibrations, and optomechanical interactions. The main experimental technique is Brillouin light scattering. For the theoretical calculations we employ finite-element-method (FEM) calculations. Moreover, we investigate laser-induced phenomena in nanostructures, such as laser-assisted self-assembly of plasmonic nanoparticles, excitation of coherent acoustic phonons in nanomembranes with femtosecond laser pulses, and light-to-motion conversion in bioinspired polymer nanomembranes.