I'm playing a mage with 90 MA right now, inventors and the like won't serve me. But I still want Magnus to make featherweight chain mails and elite plate mails. Especially, since there are very few good large armours for Sogg, the tank.

Someone got an idea where to get it in a chest or (even better) to circumvent the mage ban in inventor stores?

Thanks in advance.

You can obviously steal or rob the inventors, if roleplaying allows it.
If there is a spool in a container, it is surely in the dwarven mines (especially wheel clan). There are a lot of tech ingredients there, but I don't know them all.

Maybe there are also some bugged dialogues you could use, if you are shrinked/dumb/invisible, or something. This thread would imply so: http://www.terra-arcanum.com/forums/index.php?threads/powerful-mages-can-still-buy-at-tech-stores.2992/

It occurs as a found item in dungeons, especially tech-heavy ones like the Dredge.

But you're SOL anyway, unless you hack Magnus's leveling scheme. No tech follower learns past level 4 on their own in the two disciplines they know;* only you yourself can advance high enough to ever build those items.

(*Franklin Payne is even worse. That mustachioed poser only ever learns the first level of all eight tech disciplines, making him little more than a Swiss Army knife with very dull blades. Just so you know.)

For the inventor shop in the Wheel Clan, in his unlocked backroom, if you position yourself right you can use Unlocking Cantrip on his inventory container without him hearing you and then take any tech stuff you want out of that. It's what I used to do when I made Automatons with a magickal character.