I have often been asked by low vision users who are switching to the Mac or who are interested in doing so if there are modified large print keyboards or overlays for keyboards specifically for the Mac. I hadn’t had a clear answer to this question, but now I do. AISquared, the makers of the ZoomText products for both Windows and the Mac, also sell large print keyboards and keyboard skins for Apple keyboards. The keyboards themselves are actual Apple keyboards, but have different color contrast options for the large print characters. These products are simply awesome for folks who need keyboards with large print or have an Apple keyboard, but would like an overlay to help them see the keys better.
You can get all of the details
here.