In a large mixing bowl, cream butter and sugar until light and fluffy, 5-7 minutes. Add eggs and vanilla; mix well. Combine the flour, baking powder and salt; gradually add to creamed mixture and mix well. Chill for 1 hour or until firm. , On a lightly floured surface, roll out dough to 1/4-in thickness. Cut out with 3-1/2 in. cookie cutters of your choice. Using a floured spatula, transfer cookies to greased baking sheets. Bake at 375° for 8-10 minutes or until lightly browned. Cool completely on wire racks., For icing, in a large bowl, combine confectioners' sugar, water and meringue powder; beat on low speed just until blended. Beat on high until stiff peaks form, 4-5 minutes. Keep unused icing covered at all times with a damp cloth. If necessary, beat again on high speed to restore texture., Using pastry bags and small round tips, ice cookies. Let stand at room temperature until frosting is dry and firm, several hours. , For each color you use, in separate small bowls, combine 1/2 teaspoon food coloring with 2-3 teaspoon water. Pour onto food-safe stamp pad or folded paper towel. Press stamp gently onto pad, ensuring an even coating of coloring adheres to stamp. Press stamp gently onto dried icing. Repeat with remaining cookies. Let stand until dry, several hours. Store in an airtight container.