The invention features methods of making devices, or nullplatensnull, having a high-density array of through-holes, as well as methods of cleaning and refurbishing the surfaces of the platens. The invention further features methods of making high-density arrays of chemical, biochemical, and biological compounds, having many advantages over conventional, lower-density arrays. The invention includes methods by which many physical, chemical or biological transformations can be implemented in serial or in parallel within each addressable through-hole of the devices. Additionally, the invention includes methods of analyzing the contents of the array, including assaying of physical properties of the samples.