Question 631784
Here is a cross section of the bundle of tubes, tied with a red string:
{{{drawing(300,300,-7,7,-7.8,6.2,
circle(0,0,2),
circle(0,4,2),circle(0,-4,2),
circle(-3.464,2,2),circle(3.464,2,2),
circle(-3.464,-2,2),circle(3.464,-2,2),
red(circle(0,0,6)),
red(circle(-3,-5.2,0.2)),red(circle(0,0,6.1)),
red(line(-3,-5.2,-3,-7.6)),red(line(-3,-5.2,-5.4,-5.5))
)}}} The radius is 2 cm for the small circles, 6 cm for the large, red one.
The length (in {{{highlight(cm)}}}) of string needed is 2 times the circumference of the red circle plus:
{{{2*(2*pi*6)+5=24*pi+5=highlight(80.4)}}} cm (rounded to the millimeter).