You can make a lanyard like the lifeguards use to wear their whistles. Start with a round braid. When you get twice the lenth you want to end with, loop the working end back over a few inches from the beginning a weave a square braid with the beginning round braid end inside the square braid. You usually see this done with plastic craft strips and the square braid can slid up and down so one can adjust the loop. But with other material, the square braid doesn't slide.