Make three stacks of 12 diapers each. Tie each stack together with yarn.
Place the stacked diapers in a row, bottom side up, to make a rectangular shape. Tie a piece of yarn around the three stacks to hold the rectangular shape. This rectangle becomes the base bed for the cradle.
Cut a piece of fabric to fit around the sides of the diapers. Glue the fabric piece to the diapers with hot glue to create the bed skirt. Tie a large ribbon or lace around the top of the fabric.
Roll 10 diapers into tubes and tie closed with yarn. Stack the tubes on one end of the cradle to make the head of the cradle. Tie the bundle of diapers to the bottom part of the bed with yarn. Open the last diaper and glue it on top of the 10 diapers to smooth the top of the cradle.
Cut a piece of fabric to fit over the headboard of the cradle. Hot glue the fabric in place. Tie a ribbon around the headboard for decoration.
Fold a baby blanket to fit on top of the cradle cake. Tie a ribbon around the entire cradle and the blanket to hold it in place. If desired, add accessories or toys to the cake by tying them in place with yarn or ribbon.