My last two baby shower gifts have been diaper cakes. They are simple to make and no worries about giving something the parents don't need. I chose Pampers swaddlers, because they are mostly white without many pictures or designs. Size one diapers seemed like the best choice, since they won't be outgrown too quickly. I purchased a package of 3-4 white cardboard cake platforms (14" size) in the cake decorating supplies at Hobby Lobby and used one to hold the diaper cake. There are lots of pictures and tutorials on various websites if you need creative ideas for diaper cakes.
supplies:
Pampers swaddlers diapers size 1 (box of 108)
Large rubberbands (3-4)
large round plate/platter or round cardboard piece for bottom
ribbon to cover rubber bands (I like to use 2 sizes, wide and narrow)
something to decorate the top (optional)
pins or glue gun for the ribbon
small dowel rod to stick down through the center of each layer
To make this especially easy, I borrowed round cake pans from a friend who makes wedding cakes. The pans held the diapers in place while I arranged them, then I slipped the rubber band over each group/layer to hold them snug.
*Cake pans and number of diapers per layer: 12"pan/44 diapers, 10"pan/32 diapers, 8" pan/20 diapers and 6' pan/12 diapers.
The layers on my diaper cake are not hooked together, so I stuck a small dowel rod down through the center of each layer to stabilize. I have also seen netting/tulle used to gift wrap/enclose the cake, which makes it easier to transport.
Diaper cakes make a pretty decoration for a baby shower and a simple crafty gift, as well.