One way to measure the distance is to use ultrasonic transducer which is cheap and robust. Paoson Woodwork constantly needs to measure distances inside room while installing furniture or doing repair work. So he came up with idea of building an universal distance meter which would measure distances in all four directions at once.
He put electronics in to his custom made plywood enclosure where he made openings for sr04 ultrasonic transducers. He put an LCD in front, along with two buttons for unit selection and function. Additionally there is a bubble level tube included to keep things straight when hanging on the wall. All you have to do is to hang the meter on the wall and it displays the distance on LCD for in all four directions. It can display the area of wall with a single button press. There are other programs available along with area and distance. These are Rel – to measure relative distance, Total – to measure total distance between two opposing surfaces.