What a great thread!
I know there is already some videos on how to build a Mouse Droid in here, but thought these may be good for alternative options:
‘Star Wars Mouse Droid Build - Ace Makes’ - 6 minute youtube video - from ‘Ace Cosplay’
‘Star Wars Mouse Droids Fan Builds!’ - 7 minute video - from ‘Adam Savage’s Tested’
‘Build Your Own Star Wars Mouse Droid’ - 5 minute video - from ‘Eric Lindenberg’
& http://luckyxero.com/droids/mouse-droid-build - with instructions and images
‘Star Wars Remote Control Mouse Droid Demo’ (shop bought official product review) - 3 minute video - from ‘Jason Sasaki’