You can't place the marble (preferably silicone gel) into the healing belly button for several weeks until the incision is already "dry" which is usually approximately two weeks after surgery. At that point, patients that need it or want a slightly larger, rounder belly button use the silicone gel marble under their Spanx or other garments for anywhere from several weeks to several months. Most patients don't need to use a button at all!!!
Web reference: http://www.sadehsurgery.com/tummy_tuck_gallery.htm