The Lo Ban Ruler’s origin is from China; however, almost all the Vietnamese carpenters and builders use it as a system of fortune measurement simultaneously with the standard metric system of measurement, whether to build a house, a kitchen, an altar, or a coffin. The Lo Ban ruler is divided into eight sections, and each section has five scales that are around 52 cm with two colors of red and black. The color red is good, the color black is bad. I used it to check out my room and found out that the balcony door is on the good scale while the dimension from the floor to the ceiling is on the bad scale. So I remade the ruler so that the bad scale can be the good scale too. It seems that this decision makes me feel more optimistic about my fortune.