You may need to design a keyguard for a case that fits right up against the edge of the screen like in this picture:
Using the standard settings to design your keyguard can result in a keyguard that has very thin boarders and could be fragile.
You can add additional thickness to each of the four outside edges of the keyguard in the to compensate for cases that fit very closely to the edges of the screen using four options contained in the “Tablet Case” section:
You can choose to add an arbitrary amount of additional thickness to each edge of the keyguard, as necessary. The thickness you choose is added from the edge of the screen inward:
Note that the additional thickness that is added is taken from the keyguard elements that border the outside of the keyguard like message/command bars and cells on the outer perimeter of the grid. Those cells will be slightly smaller than the other cells. This ensures that the rails still align properly to the boarders of the cells.
Note that the following video was created using a version of keyguard.scad before it was possible to add plastic to each of the four edges, independently.
The following video shows how to add thicker perimeters to a keyguard design:
The following video shows an example of a keyguard before and after thicker perimeters were added: