I believe that this cap eagle is a current reproduction being sold in Poland.
In 2010 in Chicago at the PNA camp I participated in a 1939 campaign re-enactment.
There was a Polish vendor there selling about 8-10 different Polish insignia (cap eagles, breast badges, ) all cast with very similar spin discs.
From a few feet away they look good.
I bought a number of them and use them in my impression......just can't be wearing the originals out on the field.