Region used for material orientation assignment can also be used in meshing a part. Here is an example of messing a part using C3D8R element.
Some Python codes for build Region in Abaqus are really difficult to figure out although Abaqus has a lot of examples and detailed manual and reference. Here is an example for creating discrete material orientation using Python script.
To help my colleague to catch up on the finite element simulation of ballistic impact on a fabric based on a yarn level model in Abaqus, I recorded this whole procedure for sharing.