One movable light on a single form. Source size sets the width of the terminator - the line where light turns to shadow: a point source cuts a razor edge, a broad source melts it into a gradient. Distance does two things at once: bring the light close and the terminator softens while the falloff across the body steepens; pull it far and the terminator hardens while the light flattens out. Drag the light behind the form to raise a bright rim along the silhouette.