Drawj2d creates technical line drawings using a descriptive language. It writes pdf, svg, eps and emf vector graphics or png images. It runs on all platforms that run Java.
It is inspired by Asymptote but with a tcl-like syntax and 2D only.

Fachwerk calculates strut-and-tie models used by structural
engineers for analysing and designing reinforced concrete structures.
The program only uses equilibrium conditions, thus it does
not assume elastic material behaviour.

Fachwerk3D calculates spatial strut-and-tie models used by structural
engineers for analysing and designing reinforced concrete structures.
The program only uses equilibrium conditions, thus it does
not assume elastic material behaviour.

With Mavscript you can do calculations in a text document. Mavscript
processes template files containing text + algebraic expressions (or
java code). Text files, OpenDocument Text odt, LaTeX tex, hypertext
html and other text based formats (i.e. svg) are supported. The
text file may be packed in a zip-archive.

How it works: Mavscript reads the calculation commands in the template.
These commands start with the control characters §m and end with one of
the following control characters: §i (print input), §o (print output),
§io (print both input and output) and $n (do not print anything). The
commands are forwarded to a Computer-Algebra-System. The algebra pro-
gram returns an answer to Mavscript, i.e. the result of the calculation
command. Mavscript now can insert this answer in the text, where the
command was.

The standard engine is the built-in computer-algebra-system Yacas. The
built-in java-interpreter BeanShell or Jasymca may be used instead. The
last option is to connect to a port (on localhost or a remote server).