Hold the lighter close to the end of the drawstring until it starts to melt slightly.

Once the end of the drawstring is melted, let it cool down and harden. This will seal the ends and prevent fraying.

Repeat the process for the other end of the drawstring.

Be very careful when using the lighter to avoid burns or excessive melting. To achieve sealing without burning, only hold the flame to the drawstring for a short time.