Collages have been a common form of artistic expression since their first appearance in China around 200 BC. Recently, with the advance of digital cameras and digital image editing tools, collages have gained popularity also as a summarization tool. This paper proposes an approach for automating collage construction, which is based on assembling regions of interest of arbitrary shape in a puzzle-like manner. We show that this approach produces collages that are informative, compact, and eye-pleasing. This is obtained by following artistic principles and assembling the extracted cutouts such that their shapes complete each other.