OK this may be slightly relevant to this thread.

Thought of a (full) SD inside N770. After looking inside extensively I decided the "metal part" housing the battery is the best place. Behind it is a rubber insulator to the LCD - so I thought of cutting the metal and placing a SD card and solder wires directly on the card (at least I need not open it fully next time I need to change/upgrade it).

(Un)fortunately the metal is of such good quality that no amount of drilling can cut it (see image). Currently I have removed (part) of the rubber insulator and placed the SD card in that place. Hope this will be helpful.