Carbon nanostructures fabricated using focused electron beam induced deposition (FEBID) in a residual vacuum atmosphere or in the presence of low pressure precursor gas exhibit enrichment with the atoms of the substrate element. Nanostructures having base sizes up to 100 nm and height up to 250 nm with maximum substrate atom enrichment of 50% have been fabricated. The size of the structures (nanocones) and the substrate atom enrichment depends on the electron beam current density and irradiation time. A possible explanation of the phenomenon has been sought on the basis of local temperature rise and diffusion of the substrate atoms in the nanostructure during the growth process. The phenomenon can be used to fabricate dense 2D carbon nanopatterns enriched with a desired element used as the substrate material.