Start with a line PQ and a point R off the line. 

1. Draw a transverse
line through R and across the line PQ at an angle, forming the point J where it intersects the line PQ. The exact angle is not important. 

2. With the compasses' width set to about half the distance between R and J, place the point on J, and draw an arc across both lines. 

3. Without adjusting the compasses' width, move the compasses to R and draw a similar arc to the one in step 2. 

4. Set compasses' width to the distance where the lower arc crosses the two lines. 

5. Move the compasses to where the upper arc crosses the transverse line and draw an arc across the upper arc, forming point S. 

6. Draw a straight line through points R and S. 

Done. The line RS is parallel to the line PQ 
