They can download and print out the flags I've drawn; either in full colour, or blank line drawing versions which they can colour-in themselves!
Step 1: To make the flags, you will need:
Clean lolly sticks (or bamboo skewers, cut in half, or pencils, or plastic straws)
Step 2: Print and colour-in the flags
You could also print onto interesting paper, for example brown kraft paper cut to A4 size to fit in your printer, or other coloured paper.