Numismatikforum

The connection here is a temporary change in metal. A wartime need for nickel changed the composition of the 1942-45 American 5-cent piece from 75% copper-25% nickel, to the 56% copper-35% silver-9% manganese composition visible in this example dated 1944P. (The large mintmark was intended to help recover the coins from circulation after the postwar return of the traditional copper-nickel.)....

And the very large Mexican bronze 20-centavo coin—at 15 grams, a much heavier coin than the familiar big British penny at 9.4 grams—was first used in 1920 when the price of silver hit a peak in the aftermath of WWI. The price of silver soon moderated and the usual small silver piece returned almost immediately, but the very large bronze 20-centavo coin was revived for a final time—again in response to high silver prices—with these coins dated 1935. Metal prices moderated once more, however, and the usual small silver 20-centavo coin soon returned.

v.

The wartime US zinc coated steel cent would have its place here, too. Sadly enough I don't have any to show here.
The surplus of unused planchets became the Belgian 1944 2 franc pieces. Again I can't contribute a picture
Sigi

-

I happen to have a pair of pictures, Sigi, so please let me round out your thought. This Philadelphia-mint 1943 American 1-cent was an unsuccessful wartime expedient whose zinc-plated steel composition led to frequent confusion with the 10-cent coin. Production of the steel cent ended after only a single year....

...but 25,000,000 of the unused ’43 planchets were used by the Philadelphia mint to strike these 1944 Belgian 2-franc coins.

v.