The only reason i said 'not ideal' is because i was attempting to concept-build according to your OP-- mage (preferably sorcerer), heavy armour, still-spell.
I made this build some time ago for techsmith which garnered even Valefort's praise:
http://nwn2db.com/build/?284416
You can make tweaks to it like omitting craft wand for another metamagic, but the essence of the build was to be an 'engineer' with unparalleled technical knack.
To build the same with heavy armour, take FTR or CLER instead of ROG, lower DEX to 9 and put up STR, take Still Spell instead of Craft Wand (and take it at lvl 9, pushing Practiced Spellcaster to lvl 18) and take 3× Auto-still in epics.
I personally prefer the rogue version!
The only other changes i would make is maxxing out diplomacy to make use of True Name summoning mechanics (those did not exist when i originally made that build), min-maxing INT to start at 18 instead of 17, and spending 1 epic feat on Epic Spell Focus: Conjuration. You can also dump rogue entirely and just go Wiz 15. This will get you 2 extra feats (one pre-epic replacing Practiced Spellcaster, and one extra epic bonus feat)
Have fun.