Expandable case parts/kits


I was looking all over google for possible expandable case parts for the PI 3.
I saw the one that was a pcover part for the screen. for example.

I was looking for parts that allowed you to expand the case up few layers to accommodate a add on stacked board ( adafruits ultimate gps module for instance)

Then I also saw the one about our PIPHAT DAC boards and thought it would be nice to have one for that too?

Maybe other boards addons? generic moddable layers?