Something you’ll likely hear me referring to a lot – It’s my rule of thumb for determining if something can exist in the WU.
Long and short of it is that a lot of knowledge, especially common knowledge, managed to survive the first hellish century, either through the work of one of the scholarly orders, or just through the effort of scavengers and dealers in information.
And up until the industrial revolution (1760 – 1840 for the purposes of this discussion), most things were manufactured by a skilled artisan, or a series of them; hell’s bells, you didn’t really start running into things that needed mechanical/industrial set ups until into the 1900’s.
Anyhow. End result: If you can successfully argue that something could be made, from scratch, by a single artisan, using modern knowledge, it’s probably being made somewhere in the WU.