They are a euc instructions for DIY made years ago http://www.instructables.com/id/Electric-unicycle-Arduino-DIY/
It can be updated with hub motor and wide pedals. Would be nice to have a collaborative open source project euc made in electricunicycle.org
They are lot of features to discuss, like size, weight, power... but because is a open source project, the most important features is the scalability and compatibility.
Firs the scalability allow more people access to the product.