Summarize:

Place the cake on a piece of cardboard and outline it with a pencil. Remove the cake and cut the circle out of the cardboard. You could also place your cake on a decorative plastic tray or a cheap pizza pan. Make sure that the rubber bands are covered. Cut the ribbon so that both ends overlap slightly. Secure the ribbon together by taping the two ends together. You can wrap more than one type of ribbon around the cake. Wrap each layer in a different type of ribbon or wrap a large ribbon around each with a thinner ribbon layered over the larger one. Add fake flowers to the cake by sticking the stems between diapers. Stuff colorful pieces of tissue paper down the paper towel roll (if you used Method Two) and add flowers coming out of the top. Go to your local craft store and see what decorations you can find. You can also add baby travel sized products for extra flair. (This is an optional step.) Tie the netting together at the top with a bow, or add a stuffed animal to the tie for a "topper" to the cake.
Create the base for the cake out of cardboard. Wrap a ribbon around each layer. Place decorative embellishments on the cake. You can wrap the diaper cake in cellophane or netting to help with transportation.