And 10% Dick. Arrrroooooooo!!

The list of Bender's claimed composition adds up to over 100%, so he can be a dubious source (episode codes in brackets):

40% Zinc (1ACV13).

40% Titanium (2ACV03).

30% Iron (3ACV22), presumably mixed with osmium, (3ACV17).

40% Dolomite (4ACV07).

40% Lead (video game).

40% empty (s07e09)

40% back (s7e21 Assie come back)

0.04% Nickel impurity - (3ACV17 - A Pharaoh to Remember)

There was also a claim that he was 40% chromium (not made by Bender but by someone else - 6ACV03). In addition to those, he's also claimed to be 40% horseshoes (ITWGY), 40% Wire (7ACV03) and 40% scrap metal (6ACV23), either of which could be any of the above metals or something else.