Fold a snowflake beginning with the creation of a hexagon from square paper. Opportunities for variations will be pointed out as they occur.
The Greatest Dream Origami (Snowflake) p.82-86 ISBN 978-4-255-00505-8
Origami and Math: Simple to Complex (Hexagon) p 13 ISBN 978-0-486-48886-8
At least 6-inch (15 cm) kami will be great for this. Larger will be easier for less experienced folders. Fancier paper is certainly an option once the folds of the model are understood. Scissors will be needed but only for the creation of the hexagon.