[Deschodt]

I did it all myself, what spendy tool ? I tensioned with a 8mm wrench.

Did it twice actually, once with steel posts (best), once on redwood posts (not as nice).
You measure the cable length, tie it at one end with the supplied hardware, cut based on the end fitting, and use the adjustments in the hardware to tighten up. They stretch over time, so I can see when I'll eventually run out of adjustment and have to recut, it's not hard. The only tool I used was a strong cutter for the cable and 2x 8mm wrenches.

Now, it is insanely EXPENSIVE. The hardware and cables might as well be gold plated. The redwood posts have "given" a little so it's always looser there. The steel ones have not moved but it still stretches the cables over time. So I prefer steel, and tighten once a year or so. I love the look so much I replaced a pony wall near stairs in my house with more cables...