Simple window shades made from masking tape.  Take the plain old masking tape roll, the off-white color and cut a piece off to place on the inside of the building window.  Usually covering the top half of the window is the way to go to show a half drawn window shade.  But to mix it up you can cover any amount of window to show a fully drawn window shade to a partially drawn window shade.  And they do make masking tape in various colors to match your need!