Take one diaper and fold in thirds lengthwise (or to height you want). Wrap around the bottom of the baby bottle (you can fill bottle with q-tips or whatever you wish). Secure with a rubber band.
Take another diaper and do same (wrap around first diaper). Do this with the remaining diapers. Then take receiving blanket and fold to match height of diapers. Wrap around the outside of diapers and secure with diaper pins. Stuff the various items in the top of the cake "folds" (so they stick out). You can pin some lace around the cake and add some curling ribbon.