Jeffrey Stephenson made a beautiful Mondrian PC enclosure.
Mondrian is a fanless mini-ITX case design made from wood and hand-cut acrylic tiles. Fresh air is drawn into the case after passing through the exposed heatsink finning. An 80mm CPU fan is mounted under the heatsink and acts as a combo CPU/case fan.
Specific inspirations (including the famous Yves Saint Laurent dress) and a build report at the above link!