I have now made an Arduino shield version of my voice changer project. This has been quite the learning curve, learning to layout PCBs using Eagle. Having a finished board makes this project feel much more professional and complete and I'm very pleased with the results. This is my first PCB design and it was a fun project.
I'm making a small number of these boards available on Tindie for $29.99 plus shipping. I'm curious to see if there's any interest for a board like this. Click here for the product page on Tindie, which has a demonstration video too.