Re: I would like
Have you tried machining polycarbonate? Try it on an old CD. It's better moulded, or pressed (which can be done at room temperature for some forms).
Multicore chips are an effort to save battery power - the idea is that fewer / efficient cores are used for keeping the phone ticking over, and the other cores are only called into action when required.
If you want a solid aluminium, dual core phone with a 4" display, you might consider a Sony Xperia P- and it's not too pricey. Okay, it doesn't have a removeable battery, but i get on quite well with with a little Li-ion USB battery pack I bought from Lidl. It doesn't have a uSD card slot, but it does support USB OTG, so a card reader can be connected (note: the Nexus 4 doesn't offer this facility). The Xperia P doesn't have stock Android, but the Sony customisation isn't too offensive.
Its camera is alright, but nothing special in low light. There isn't really any substitute for size when it comes to low light pictures (bigger sensor, brighter lens), so maybe you want a Nokia Pureview or a dedicated compact camera.