I could not resist!!
I know, I probably paid much to many but something told me I had to do it.
I bought the Golden Ducat end Double Ducat from the Royal Dutch Mint.
https://www.knm.nl/gouden-dukaten-2018/nl/page/2781/
Is this what they call stackitis? It probably is.
For info on the coins, see YouTube movie.
Enjoy