30 degrees marking ruler

My roof has a 30 degree angle. During work in the attic, I needed to mark a lot of cuts, wood and isolation material at 30 degrees. Putting the angle protractor at 30 degrees and trying to hold in flat against the material… Made a simple marking ruler to mark 30 degree cuts. It has a support to make hook it on the edge of the material to make accurate marking quick and easy.You can use the inside or outside side of the ruler. Approximately 11 x 8 cm