I keep alive a copr repo [1] and there are options to build for epel - I'm testing a build right now (see P.S. failed). With calculix there is a bit more fun because there is some missing fortran library (at least in fedora), but again that something that can be compiled from the source. If you have access to the system, FreeCAD building script from wiki is probably a good starting point. We have freecad.spec in the FreeCAD source [2], so we can try to extend it to include CentOS or RHEL. I need to dig deeper into rhel/centos - I'm fedora user for a long time, but I don't need very stable distro.
I'll be happy to help with the compilation if you go that way, but it may end up being a huge task depending on wat's missing.
[1] https://copr.fedorainfracloud.org/group ... cad/coprs/
[2] https://github.com/FreeCAD/FreeCAD/blob ... eecad.spec
P.S. FreeCAD builds for epel6/7 fails with some missing dependencies (Inventor-devel is the common one):
https://copr-be.cloud.fedoraproject.org ... r-live.log
https://copr-be.cloud.fedoraproject.org ... r-live.log