The Wizard of Huz
As for penlites instead of 18650's, it's impossible, due to different chemistry - they're, most of the times, NiMH/NiCD, and we need LiIon (all it subtypes are ok).

If You or someone else know about AA LiIon's accu's offering decent capacity - or, generally, any type that would suit N900 better than 18650's, offering decent capacity and at least being half as widely available as 18650's, I'll gladly consider it as an option - 18650's pose quite big design problem due to it's size. IMO it's out-weight by pros, but maybe there is better alternative that I'm not aware of?

Also, it's not possible to disassemble 18650 and re-build it as flat battery - at least, I'm not aware of such possibilities. Maybe dr_frost_dk know something about it?

As for CAD drawings from Nokia - no way to achieve this. I don't have digital probe, so I'm just designing case by hand - knowing measurements took by hand, and sometimes, by trial and error That's why it takes time - with proper digital probe, I would probably be offering body replacements already

@fffa
No worries, of course I'll still make regular, flat covers. As for body replacement, it will be build a way, that it can be used with both flat and big cover (much like it's not with regular body, although I won't re-create original locking mechanism, probably). So, people like me would be able to have body replacement with big backcover and geeky mods, but it will be perfectly possible to use it with flat alu cover, without tripod mounting points etc.

/Estel