The five fold 3D card approach can be the vehicle for simple, but effective masks. The right language can also incorporate aspects of mathematics in a practical setting. It is a good idea for children to have practice sheet of paper first so that all folding is rehearsed before card is used.
Take one piece of A4 card.
Fold in half lengthways.
Bend the card back along the lengthways centre line.
Cut along the drawn line, through the folded card.
Open out the card.