Integrated photonics has expanded rapidly over the past two decades, driven largely by the demand for high-speed optoelectronic systems in telecommunications and data-center interconnects. Silicon remains the dominant platform, while alternative materials such as thin-film lithium niobate are increasingly adopted to extend functionality. In parallel, van der Waals materials including hexagonal boron nitride (hBN) and graphene support mid-infrared (mid-IR) polaritons, i.e., guided electromagnetic excitations with extreme field confinement well below the free-space wavelength. Despite this opportunity, systematic waveguide and device design based on van der Waals polaritonic modes remains comparatively underdeveloped. Here we design and numerically investigate a set of mid-IR polaritonic building blocks including power splitters, resonators, and input couplers based on hBN strip waveguides. Our results demonstrate that van der Waals polaritonic waveguides support functional mid-IR sensing and spectroscopy building blocks with sub-micrometer footprints. The footprint is set by the polariton wavelength, which is more than ten times shorter than the free-space wavelength. The intrinsic propagation loss is 2–6.5 dB/µm over 1400–1500 cm−1, so the platform suits short and densely integrated circuits.