Medium skills. You need yarn (Viking Eco-Alpaca, bulky, 12 ply, 7 wpi. 600 gram, 751,6 meters or 822 yards for the smallest size and 800 gram, 1000 meters or 1096 yards for the biggest size. If you choose to knit the liner you need almost twice as much), needles (6 mm/US 10), 10 or 12 buttons, depending on size, and fabric for the lining. Knitted back and forth. Two sizes: 0-6 months and 6-12 months.