Dieter,

It looks like you are confusing dimensionality of the array with the dimensionality of a vector that it might store.  If you are interested in using numpy for 3D modeling, you will likely only encounter 1-dimensional arrays (vectors) of size 3 and 2-dimensional arrays  (matrices) of size 9 or shape (3, 3).

A 3-dimensional array is a stack of matrices and the 'right-hand-rule' does not really apply.  The notion of C/F-contiguous deals with the order of axes (e.g. width first or depth first) while the right-hand-rule is about the direction of the axes (if you "flip" the middle finger right hand becomes left.)  In the case of arrays this would probably correspond to little-endian vs. big-endian: is a[0] stored at a higher or lower address than a[1].  However, whatever the answer to this question is for a particular system, it is the same for all axes in the array, so right-hand - left-hand distinction does not apply.