This is a picture of my Raspberry Pi model B 512MB in an 8mm videotape case:
The finishing is not perfect, I am not very skilled in plastic works. At first, temperature reached 58ºC. After making some holes on top of the SoC, temperature lowered to 50ºC. I suspect that the Lan chip is hotter than the SoC, as you can see in this post:
http://www.zipfelmaus.com/blog/raspberry-pi-thermal-images/
electric-safari 