Hexi
A dedicated process for hexahedral mesh generation.
Hexi is a standalone Linux platform, Docker sphere, or Windows executable for generating unstructured hexahedral mesh. It hosts a remarkable program capable of consistently producing an entirely hex mesh of good quality, suitable for finite element analysis.
Hexi's documentation is split into three parts, and can be examined here: https://hexi.sourceforge.io/Hexidoc_Part1_211026.pdf,
https://hexi.sourceforge.io/Hexidoc_Part2_210716.pdf, and
https://hexi.sourceforge.io/Hexidoc_Part3_211211...