An apparatus for separating solids from a suspension includes a hollow cylindrical column having a central axis therethrough. Each of the sheets comprises sheet sides and sheet edges between the sheet sides, wherein the content is printed on at least one of the sheet sides. The ring is coupled to the housing at a plurality of embossments either by welding or mechanical couplings. By blocking portions of the x-ray beam focused on the thin film and generating reflectivity curves in increments, the effects of scattering can be minimized. This can be used, for example, to provide a tactile feedback when the user depresses the pointing stick to cause a mouse click.