Problems using CalculiX with FreeBSD have been reported on the mailing
list for that application. There seem to be no difficulties using it
on Linux, but problems with OpenGL have prevented many of those trying
to use it on FreeBSD, including me, from getting a satisfactory
display. Has anyone here had such difficulties and discovered how to
overcome them?

The problem with SLFFEA (San Le's Free Finite Element Application) is
that it's very difficult to get enough information about it to enable
a beginner to use it. The FreeBSD port puts all the free-standing
binaries (with names like bm, pl, etc.) in /usr/local/bin. I'm not
sure where the examples are, though, and other documentation is far
from complete. This looks like a nice program for civil engineers, so
perhaps such a person would know more about it.