Go to your local hardware store, big box store, and look for zip ties - electrical section is most common but they could be in multiple sections. Get a length that is long enough to go through your zippers.

We've been using purple ^

And if my clippers are ever taken by security (that has never happened, though I've had corkscrews confiscated) the hotel front desk has always had some implement to help me cut the zip tie upon arrival. Or friend/family if I'm not staying in a hotel.

http://www.cabletiesandmore.com/amer...k75xoCbhDw_wcB