Step 1: Mark two points P and Q on the given line l.
Step 2: Using set-square, draw a line perpendicular to line l from point P.
=> Now, from another point Q on line l, draw another line perpendicular to Q.
Step 3: Place zero of the scale at point P and measure 3.5 cm on the line perpendicular to l, passing through P.
=> Mark the point as A.
=> Place zero of the scale at point Q and measure 3.5 cm on the line perpendicular to l, passing through Q.
Step 4: Join A and B.
=> Extend the line to the left of A and to the right of B.
=> Mark the line as m.
=> Line m is the required line parallel to line l at a distance of 3.5 cm from it.