What Can Be Done to Make It Easier to Set

What can be done to make it easier to set the root opening for tack welding?

A) Bend a piece of filler rod in a U-shape and place it between the ends of the pipes.
B) Use a piece of tungsten as a spacer because it will not melt and it is hard enough to resist the forces of the tack weld bead shrinking.
C) Measure the gap carefully with a steel rule or tape measure.
D) Using a smaller diameter nozzle cup, place it in the groove to keep the pipe ends spaced as the tack weld is made.