This is how I put a bowstring on a 1/72nd scale figure...I have tried other ways, thin copperwire (too heavy and it needed painting which made it too thick), human hair..(it drys out and breaks)
and many others.
With this one I use the bristles from a normal house paint brush.
The tools needed;
Second glue, tweezers, paintbrush and finescissors (here nailscissors)
It´s pretty simple really...cut a fine bristle off the brush . It has to be a bit longer than needed to span the two ends of the bow.
Put a bit of glue on each end of the bowstave and attach the bristle. One end can be attached flush to the bowstave, whilst the other end can be a bit longer. When the glue has dried, simply cut off flush to the bowstave and paint over.
This works fine for archers that are loading or have fired, but for the ones that are drawing thier bowstring, it´s more or less the same method except the bristle needs cutting into two short lengths and attaching from hand to stave.