Key guides are used by people who aren't able to speak and don't have fine motor skills. The guide assists talking apps which have pictures that, when clicked on, verbalize the image. Using the guide, one can feel when they are about to enter a new box and can have more control over which box they press.
I created the below model using Onshape and fabricated two on a laser cutter using eighth inch clear acrylic. Here is the onshape file.
Since there are many different language apps, there are countless layouts that are needed and practically every person uses a different layout. Because of this, it can be hard and expensive to get everyone the best keyguide and language app. Here are a few other layouts that I made.