qcad (Open Source CAD)

QCAD is a free, open source application for computer aided drafting
(CAD) in two dimensions (2D). With QCAD you can create technical
drawings such as plans for buildings, interiors, mechanical parts or
schematics and diagrams. QCAD works on Windows, Mac OS X and Linux.

To build qt4 version of qcad (requires a qt4 version library installed)
run the SlackBuild with QT5=no:

  # QT5=no ./qcad.SlackBuild