Just a heads up, the MappyDot should be in stock on the Tindie store around the end of this month. The ATMega328PB MCU's have been out of stock for a little while worldwide, with a long lead time. However I have managed to secure quite a few of them to get the ball rolling.
The product page is now online if you would like to add the MappyDot to your wish list.
The firmware for the MappyDots is about 90% complete, with just a few little features to test out and tweak. The sources will be released at the same time the MappyDots become available for you to peruse. A Fritzing part is now available in the repositories.