According to examples, a non-transitory computer-readable medium may have stored thereon instructions that may cause a processor to identify a first porosity level range that a first portion of a layer of build material particles is to have. The processor may also determine a density level at which an agent is to be deposited as droplets onto the first portion of the layer of the build material particles to cause the first portion of the layer to have a porosity that is within the identified first porosity level range. The processor may further store the determined density level, in which an article including the first portion having a porosity level that is within the identified first porosity level range is to be fabricated from the build material particles based on the determined density level.