This is an article on a study conducted on Goffin's tool making by giving them different materials to work with and a problem to solve (how to get to the food). Scientists found that they adapted their toll making technique to suit the material they had been given (with the only material they couldn't manage been beeswax which, as we all know, it's way too soft for those powerful beaks) and that they made the tools of almost the exact length they need it. How cool is that?!
https://www.sciencedaily.com/releases/2 ... 210016.htm