To make a wearable hat you need to use a stiff type of school construction paper called bulletin board paper. It's coloured on one side and white on the other. Try your local school supplies/educational shop.
For an adult hat you need 60cm square of blue paper and a 20cm square of red paper.
For a child's hat you need a 50cm square of blue paper and a 17cm square of red paper.
The quick option is to draw on the eyes using a marker pen. For a more professional look first draw them onto white sticky-back paper, then cut out and affix.
Download the paper-folding instructions using the link on the right.
Download printable version:
[656 KB, PDF]