In 2009, NUST sponsored a visit to Orlando, USA to present research work at BCBGC-09. Few pictures are posted here (courtesy of Syed Nayyer Abbas Kazmi, IIU, Islamabad).
Dia is an application available at LINK to create technical diagrams. A very useful, however, requires sparing sometime to learn. For starters, you may need to try "Toggles snap-to-grid" and "Toggles object snapping." Further, on properties set Font and Font size.