Place marzipan on parchment on a flat surface. Add ½ teaspoon powdered food color and knead it into the marzipan until color is consistent. Roll the marzipan to ⅛ - ¼ inch thick. Use a small bat cookie cutter to cut 12 bat shapes. Set aside, uncovered, to dry/harden at room temperature.
Make twelve 2 inch long strips and roll them back and forth to round the edges. Curve the strips slightly on one end and set them aside to dry, uncovered, at room temperature. Cut 24 small triangles for ears and also set them aside to dry at room temperature.
Make icing by combining the confectioners’ sugar, milk, corn syrup, almond extract, and ¼ teaspoon of powdered food color in a small bowl. Whisk until smooth and fully combined. Place the icing in a piping bag or freezer bag with one corner cut off leaving a small hole.
When the marzipan has dried, make the bats by piping a line of icing in the center of the marzipan bat and gently pressing a blackberry in place to make the bat body with the bottom of the berry pointed down to support the bat. Lay the bat on its back to allow the icing to harden. Repeat for the other berries.
To make the cats, stand a berry upright with the bottom of the berry as the base. Pipe a half inch line of icing at the bottom of the back of the berry. Press the straight end of a marzipan tail to the icing. Lay the berry on its side with the tail under to allow the icing to harden. When the icing has hardened, stand the berry upright again and pipe a short line across the top of the berry. Press two triangles into the icing to form the ears. Repeat for the other berries. Allow to dry completely before serving.