Mass and density distribution of SN ejecta are presented in the velocity space. Top left: enclosed mass of the ejecta as a function of the ejecta velocity is shown. The He, O, and Si-cores are marked on the figures, with the respective mass-velocity boundaries (see Sect. 2). Top right: fractional abundances of the elements (H, He, C, O, Ne, Mg, and Si), taken from Rauscher et al. (2002), are shown as a function of ejecta velocity, where the mass-velocity relation can be derived from the figure on the left, as shown in Sect. 2. Bottom left: distribution of gas (number) densities in the ejecta, as the function of velocity at 100 days post-explosion (see Sect. 2.1). The densities for uniform ejecta are shown for reference, but we only model the scenario of clumpy ejecta. Bottom right: volume filling factor for the clumps are shown with reference to Eq. (5).