We bought a box of diapers at Costco (size 1-2) and used one entire half of the packaged diapers with about 4 left over. I didn't have rubber bands so I hand tied each rolled diaper with twine. For the middle, I unrolled a half used paper towel roll and used the center as...the center for the cake! Some people used baby shampoo. I would have done that if I wanted to run to the store for the 4th time for the cake, but I was strapped for time.
Her baby shower theme was pink and gray. I'd say I did a pretty good job with the time and resources I had!