I used yarn Alize Cotton Gold (55% cotton/45% acrylic; 100g - 330mt/361 yds; hook size 3,5-5 mm), but any other yarn fits for amigurumis can be used.
Using 3 mm crochet hook their size: height of the balloon (together with the basket): cca 16 cm
Pattern can be used to make a baby mobile, a wall hanger or any decoration.