Building QSpeakers:

 Pre requisites:

  Install Qt5 and the Qwt6 library, compiled against Qt5.
  Don't forget to install the development header files too.
  If yo do not have Qt5 in your distro, you can install Qt4 and
  Qwt6 compiled against Qt4. This has been tested and is known to work.

 Compilation:

  You can use both command-line compilation or QtCreator.
  See below:

 In short, for Qt5 on ubuntu Xenial, this should do the trick:
  $ sudo apt-get install qt5-default qttools5-dev-tools libqwt-qt5-6 libqwt-qt5-dev libqwt-headers
  $ cd qspeakers
  $ qmake -config release && make && sudo make install

 Or, for Qt4 for older debian or ubuntu, this should merely do the trick:
  $ sudo apt-get install libqt4-dev libqwt-dev qt4-qmake
  $ cd qspeakers
  $ qmake-qt4 -config release && make && sudo make install

Using QSpeakers:

  Start it by your window manager's menu, or /usr/local/bin/qspeakers from
  a shell. Choose a loudspeaker, or create a new one you want to build an
  enclosure for. Change the box parameters (volume, ...) or click 'Optimize'.

Contributing:

  If you want, you can read TODO and start contribute, or write litterals translations in your own language.

Thanks:
Thanks to Upacesky for his drawing: https://openclipart.org/detail/202508/

Happy DIY!
