Spong Coffee Mills: A Grinder for the 23rd Century - Home-Barista2 and it is identical to the Spong-labeled grinder and only about thirty years old. All of the above grinders are made of cast iron using sand.girnder for spong iron,Spong Coffee Grinder | SPONG COFFEE MILL GRINDER CAST IRON. £35.00; Buy it . vintage Spong coffee mill Coffee Grinder-Black Cast Iron made in.England. £49.99.