Draw a lines to divide faces and construct geometry.
A line can be draw on all the X, Y and Z axis and also on existing geometry. When you're snapped to an axis a colored line will extend beyond the line you are drawing. You can see the length of the line as you draw; to manually a specfic length press tab and enter that length.
X = Red
Y = Green
Z = Blue
You can see the length of the line as you draw; to manually specify a length press tab.