Rectangle Ruler / tool

In our study and work,we need to draw rectangles often.Traditionally,to draw a rectangle ,we will combine 4 straight lines together by using a ruler.However,the main problems of it are that the adjacent lines will not be perpendicular to each other and the operation will be inconvenient. To solve these problems,we designed a kind of ruler,which can be pieced together to be a rectangle and is telescopic.It is so flexible that we can draw different size rectangles in a limited scope conveniently,efficiently and accurately.