First, let the breast milk dry on waxed paper. When dry, crush up into fine powder and mix a little into about 1/2 of the part A resin, making sure not to have lumps or clumps. When smooth, add rest of part A resin, mix well, and add Part B resin, stirring carefully to avoid bubbles, then pour into mold. This worked for me. The result was a little “grainy” looking but the powder remained distributed evenly in the resin and appeared “milky” in color.