Had a few minutes to spare so decided to give this a go ~ <1 hour later & all done.
1 piece of 65mm OD muffler tube
Alternate tube size for other marque vehicle nuts
Scribe 7mm from 1 end line around tube
Draw 18 equidistant lines down to meet the scribe mark
3 cutting discs mounted on an angle grinder
Grind along the same side of each of the 18 lines carefully, with a steady hand.
Drill 2 holes @ the other end of the tube to facilitate a turning bar [not shown on the example].
Clean up & all done.
1 piece of 65mm OD muffler tube
Alternate tube size for other marque vehicle nuts
Scribe 7mm from 1 end line around tube
Draw 18 equidistant lines down to meet the scribe mark
3 cutting discs mounted on an angle grinder
Grind along the same side of each of the 18 lines carefully, with a steady hand.
Drill 2 holes @ the other end of the tube to facilitate a turning bar [not shown on the example].
Clean up & all done.