The poster (protected in a sturdy cylindrical container).
Seal the container's covers with adhesive tape, because they can fall off
in the airport handling.
Double-sided adhesive tape and scissors, pins, or Blue-tackTM
The physical object, suitably protected
Business cards with up to date contact information
An attire appropriate for the occasion - consider wearing a
T-shirt with the research project's logo
Drinking water
Reading material, to pass your time if attendance is low
Don't forget to update your web site, before you leave.
Keep copies of the promotional material (leaflet, publication)
in a web-accessible directory.
You may find them useful, if you need to print additional copies
from an Internet cafe, or a public PC room.