Convex hull on set of squares

Imagine a set of two to six squares within 3D-space. The goal is to generate a convex hull around these squares as efficiently as possible.

The following constraints are known:

  • Each of the two to six squares consists out of 4 vertices (a vertex being a 3D-vector).
  • Each vertex will be part of the convex hull (none of them will be on the "inside").
  • During the creation of the convex hull vertices may not be connected to other vertices from within the same square (otherwise the squares would "degenerate").

Is there an especially fast/efficient way to create a convex hull for this very specific geometry?