I make up my pull/pull systems out of braded stainless steel fishing leader so i always have a lot of that in the shop, like control lines it doesn't stretch. I also have a big spool of wire from installing burgler alarms, I strip it and have used that too, no stretch. Measuring like Caster mentioned was something I learned in my free flight days. Those planes have to be spot on if you want to win so perfection is a good thing. The mark one eye ball isn't always the best thing to use, my eyes are about a half a bubble off!!