This invention relates generally to novel methods of preparing self-supporting bodies and to the novel products made thereby. In its more specific aspects, this invention relates to methods of producing self-supporting bodies having controlled porosity and graded properties and comprising one or more boron-containing compounds, e.g., a boride or a boride and a carbide. The method comprises, in one embodiment, reacting a powdered parent metal, in molten form, with a bed or mass comprising a boron donor material and a carbon donor material (e.g., boron carbide) and, optionally, one or more inert fillers, to form the body. In another embodiment, both of a powdered parent metal and a body or pool of molten parent metal are induced to react with a bed or mass comprising a boron donor material and a carbon donor material (e.g., boron carbide) and, optionally, one or more inert fillers to produce a grading effect in the resultant body. In addition, combustible additives (e.g., gelatin, corn starch, wax, etc.) can be mixed with the bed or mass comprising, for example, a boron carbide material to aid in porosity production and control. When the self-supporting body of the instant invention is formed while in contact with a previously formed ceramic, metal or composite body, a bond can be formed between the two bodies, thus creating a macrocomposite body.