We describe both a method to produce a low density foam and a small mechanical apparatus used to embed a microsphere in the foam. Freeze-drying techniques offer an efficient way to create low density foams. Good results are obtained with 3%–5% of dextran in water. The density measured on samples of a few cubic millimeters is in the range of 5×10−2 g cm−3 with cell size of the order of 1 μm. The conditions which greatly enhance homogeneity and uniformity of the foam will be described. The method is well suited to a mold cavity assembly in which microspheres of 80–100 μm have been coated with foam thicknesses of 200–300 μm.