The mezuzah case, which protects the ancient biblical text on parchment, tells a story of the generations, echoing the custom to touch the mezuzah.
To honor this tradition, the indents in these mezuzah cases symbolize the human touch.
There are simple indents, which form the Hebrew letter shin. It can be a touch on its corner, or a fragment of ancient Roman glass embedded in the mezuzah case (or broken glass from a wedding) that forms a link between the past and the present.
The Birkat Kohanim Priestly Blessing mezuzah, which gently curves out from the wall, symbolizes this cherished blessing.