Never underestimate the importance of a needle and tread whilst traveling. This would fit easily anywhere within your luggage or in a pocket (though if you put it in a coat or pants pocket, be careful, of course).
“A travel sewing kit, much better alternative to the small spool-in-a-box version. Cotton thread to be used on all fabrics, 8 strands per color, 21 colors in total. Pull a thread out piece by piece.”
Cotton Thread and Needle
18″ x 1″