Various techniques to manufacture low-density metallic foams containing sub-millimetre or even micrometre-sized pores are discussed and first trial experiments presented. Three strategies are evaluated: use of an intrinsic blowing agent, foaming under high pressure and foam control by mechanical pressure manipulation. In all three cases, average pore diameters well below 1 mm could be achieved for some aluminium or zinc-based foams while keeping the relative density in a range between 20 % and 50 % of the full metal density.