You will need

Cardigan
0-6 months (16in Chest) - 2 x 50gm Balls       4 Buttons
6-12 months (18in Chest) - 2 x 50gm Balls     4 Buttons
1-2 years (20in Chest) - 3 x 50gm Balls          4 Buttons
2-3 years (22in Chest) - 3 x 50gm Balls          5 Buttons
4-5 years (24in Chest) - 4 x 50gm Balls          5 Buttons
6-7 years (26in Chest) - 5 x 50gm Balls          5 Buttons

Waistcoat
0-6 months (16in Chest) - 1 x 50gm Balls
6-12 months (18in Chest) - 2 x 50gm Balls
1-2 years (20in Chest) - 2 x 50gm Balls
2-3 years (22in Chest) - 2 x 50gm Balls
4-5 years (24in Chest) - 3 x 50gm Balls
6-7 years (26in Chest) - 3 x 50gm Balls

4mm Needles
3.25mm Needles