The fabrication of plasmonic 3D microstructures is still a challenge. In this study, the fabrication of gold-nanoparticle (Au-NP)-filled acrylate-based micron-scale cuboids forming plasmonic 3D particles is investigated. UV curable acrylate is mixed with HAuCl₄ and spin-coated onto a fused silica wafer. UV light and heat treatment of the layer result in polymerization of the acrylate and formation of Au-NPs with a plasmonic resonance ranging from 535 to 550 nm. The plasmonic resonance wavelength decreases slightly with increasing UV dose. The resonance wavelength can be shifted by a subsequent annealing process. The decreasing resonance wavelength with increasing annealing temperature is discussed as a result of the increasing Au-NPs. The size and the distribution of the resulting gold particles in the acrylate matrix is investigated by transmission electron microscopy. The Au-NPs-filled acrylate layer is laser structured using a UV-femtosecond laser, which allows the fabrication of adjustable micro-cuboids with edge lengths down to 15 μm. The laser-cut micro-cuboids are transferred into isopropanol and the plasmonic properties of the structures in the liquid are successfully demonstrated. The presented concept allows easy and large-scale fabrication of plasmonic microstructures with independently adjustable plasmonic properties and microstructural size and shape.