I made an Emmet lego costume for Halloween this year and to make it more authentic to the original I created his badge in Inkscape in vector format. It's not 100% true to the Lego Movie badge (the shoulders are slightly different) but it's close enough that nobody will ever notice.
There's no instructions because all you have to do is print it out to whatever size you need and glue it to a piece of cardboard or foam board. You can download Inkscape at: http://www.inkscape.org/en/
Since the file is a vector image, you can scale the image to any size you want and not lose resolution.
Please let me know if you find this Instructable useful!