One of our wedding gifts was a gift certificate to the MoMa store (Museum of Modern Art). We had a difficult time picking items, but one of the things we chose is one of my favorite things that we own.
Its a Double Solar Powered Rainbow Maker!!!
Here is a photo of one you can buy online. It is no longer available at the MoMa store :(
We have had this for over a year now, and it has broken. I've had to unscrew the tiny screws and piece it back together after it fell off a window in the kitchen a while ago. I had to use tiny pliers to get the little metal teeth to grab onto the prisms again. Sometimes the gears need a little kickstart.
Overall, if this stopped working, I'd buy another one. Prisms are a great way of introducing science to your baby without even realizing it.