Just thought that I would pass this on. Ropes for seats are always difficult to look right as there is not enough weight to thread or thin string. Try using thin semi hard wire like the type flower arrangers use. Shape using two gearwheels with the wire trapped between the two wheels. Or even better use a rack and pinion with the wire on the rack . Keeps it straight. I used this for my ropes for the seats and it looks ok. Perhaps the size of the gearwheel teeth could have been slightly larger.

Robert