Electronic, distance-measuring equipements replace conventional tape-based manual measurement. These types of equipements are used in various applications from household architecture, surveying, carpentry, masonary etc, to submarines, planes, cars etc. The PDDU [Portable Distance Display Unit] is a battery operated, simple to use, tape-less distance meter, which measures upto 4 meters. PDDU is constructed using Arduino-uno, 16:2 LCD display, and the HC-SR04 sonar sensor. The sturdy casing is built using metal parts, from Mechanix. [Thanks to https://www.zephyrtoys.com/] The job of tape for distance measurement is taken over by sound waves!