I love the photographs of snowflakes by W. A. Bentley. From Dover Publications you can get a CD-rom with more than 500 pictures scanned in and ready to use on your computer. This is fantastic. As it is quite hot outside I wanted to do some experiments.
To get something other than snowflakes I put together two images of one snowflake. One image is rotated by 90 degrees and thus I get an image with 12-fold rotational symmetry. The photographs are only black and white. To get colors I then converted the greys into different color hues. Finally several such pictures are combined. All this is easily done with processing in a dedicated program that selects randomly the pictures it uses. Here are some sample results: