Don't take for certain this information, but I think Prince August built some molds on the models he had in stock. There are some pieces sold in plastic "huose made" bags, that lead me to think like this.
But this means anyway that very rare figures are not available.
I know some private tried to reproduce some piece in resin, obtaining molds from the ones in metal, but the result was not so cool (they told it. I never seen the pieces).
Now... if you want a list of the figures undone, you should specify if this is intended to know if the minis were MADE in an absolute sense (they do exist, even if incredibly rare) or if they can be found. Because there is a great difference between.