It is believed that infants leave the womb with many of their senses not fully developed initially, for example, the colours infants can see best at birth are black and white. Infants vision is also not developed enough to see most things clearly unless they are about 8 to 12 inches away from their eyes.
It is a common sight to see mobiles on a baby's crib and, unfortunately, many mobiles have music to accompany them. Since infants spend a lot of time in their cribs they focus intently on the world around them (i.e. their room and its contents) and in this process learning takes place. With that in mind why not provide them with something Islamic to focus on? Below, is a file that contains some Islamic black shapes that you can mount on white poster board and make your own Islamic infant mobile. These are only a few suggestions but get creative (within Islamic bounds of course...smile) and design some more insha'Allah!
This, I feel, is worth doing because mobiles help infants develop their ability to focus and track moving objects. Try to change the mobile every two weeks insha'Allah. I hope I can insha'Allah post more Islamically themed mobile ideas in the near future. In the meantime enjoy insha'Allah.