Integrating monolayers of two-dimensional semiconductors in planar, and potentially microstructured microcavities is challenging because of the few, available approaches to overgrow the monolayers without damaging them. Some strategies have been developed, but they either rely on complicated experimental settings, expensive technologies or compromise the available quality factors. As a result, high quality Fabry-Perot microcavities are not widely available to the community focusing on light-matter coupling with atomically thin materials. Here, we provide details on a recently developed technique to micro-mechanically assemble Fabry-Perot Microcavities. Our approach does not rely on difficult or expensive technologies, and yields device characteristics marking the state of the art in cavities with integrated atomically thin semiconductors.