Drinks cooler heat sink design

[neuropie]

I'm trying to make a drinks cooler using Peltier modules, and am at the stage of making the pieces of metal to wrap around the can. I can make the pieces firstly out of wood using the CNC mill at school, and then cast them out of Aluminium.

So I was wondering, what is the best shape for these pieces? I've attached my current designs.
Full size pictures:
http://ubuntuone.com/3lE8adRRIw6x01IwfBryMr
http://ubuntuone.com/2yVkDhXjkFtIFdkqqQ6a89

Is it worth having a smaller diameter curve towards the bottom for bottles?

The angled edges are a manufacturing constraint (CNC and metal casting), however I was wondering what people think the best angle for the curved side would be (while trying to save Aluminium). I figured that the less Aluminium, the less exposed metal for heat to radiate from.

Finally, am I correct in thinking that all cans have a diameter of 66.2mm? This seems to be quoted in quite a few places - http://goo.gl/ZIKDD

Thanks!