How I draw a marble ball

Drawing a marble ball, tools are listed below Final picture: Used tools: pasteboard (vegetal paper - light gray) 35x25 cm 1,5 mm, typically used for frames, cartonnage and binding), 9B, 7B and B pencils (Caran d’Ache grafwood), paper stomp, Ecoline, colored pencils (Caran d’Ache Supracolor Soft Artis), fibre tip pens (Staedtler Noris Club 320 Double Ended Fibre Tip Pens), markers (Tria Letraset), pens (Pitt a