This box comes sized to fit the 12x12 mat (larger box in image) as well as the 8x12 mat (smaller box shown). The larger when finished is approximately 6-1/4" x 4" x 4" and the smaller 4-1/2" x 2-3/4" x 2-3/4". You can find additional images and a full tutorial on my blog: http://jamielanedesigns.blogspot.com/2014/09/petal-boxes.html