1. To create a cosmo martini glass, shape white fondant into a dome that tapers at the bottom to simulate the top of a martini glass. Paint three-fourths of the exterior of the dome pink for the drink. Also, paint a pink semi-circle on the flat side of the dome.
2. Place the top of the glass on a quarter sheet cake covered with white fondant. Roll a strip of white fondant, and place it under the drink for the stem of the glass. Cut a semi-circle out of white fondant, and set it upright under the stem for the base of the glass.
3. For the lime, cut a ring out of dark green fondant and a circle out of lighter green fondant. Place the ring around the circle, and use an indenting tool to mark eight slices in the lime. Use the same tool to cut out two slices.
4. Place the lime on the side of the cosmo glass. Use tip No. 8 and pink icing to pipe a band attaching the top of the glass to the stem.
5. Cut circles and rings out of pink and black fondant and attach them to the cake using a steamer or water. Pipe a black shell border with tip No. 8, and add an appropriate message.