Ok looking back through the items already mentioned those bubble wands would not look out of place, they come in various sizes so you can experiment. Another favourite are the various deodorant cans, again in many sizes and often with nice rounded ends. Hairbrush is an all time classic, hairbrush handles are usually the right size, rounded and easily washable. Shop around to find some that look perfect and they won't raise attention because a girl can never have too many hairbrushes right?
Marker pens, Sharpies and similar are nicely rounded and come in small through large so again you get a range to play with, use several of the smaller ones to play stretching games.
As with any sex toys, clean them before and after use and you wont have any problems!