I was surprised to come across the following information in the program of the Technical Forum of the World Money Fair 2019:

Swipe this image to the left to see it in full.
Apparently the Royal Canadian Mint is developing ways to produce trimetallic circulation coins which is surprising as so far only Monnaie de Paris has produced such coins. And the Portuguese mint is working to produce (collectors?) coins consisting partially out of polymer like Germany did before.