A bit late, but I just found my old talk on Youtube about the prototype and this old post that I started writing. Originally this was a project from 2017. Part one can be found here.
I finally got the parts I needed to build the prototype. After putting everything together according to my schematics, I uploaded the code and it worked!
Because the code was a mess, I needed to clean it up and extend it so it would support multiple speech lengths.
I then soldered some female headers onto the prototype boards and rewired everything according to my schematics.
Here I am presenting the prototype to the Fablab Bern at their Arduino Talk series, where I also talk about 3D Printing and getting started with Arduino.
The only thing missing now is the case, which I will try to build at the Fablab Bern.