My wife and I have actually done that! In fact, she still has that thing in her box of toys. The whole experience of molding it makes for a funny story and most of her friends have seen it at one time or another as she related the story to them.
I won't steal your thread with our story, but, at least with our kit, the end product turned out as hard as a rock and not very comfortable for her to use. Still, the experience was fun!
