You can use the Create Center Elements Between Parallel Lines function in the Tools menu to create elements and their associated parts between parallel lines. The element thickness is automatically taken from the vertical distance between the two lines.
Select the lines one after the other in the work window with a mouse click. As soon as you move the mouse over the second line, you will see the element in the preview.
Material
You can select a material from the list of materials that have already been created, or edit and redefine it.