I've had this percolating in my mind for a while, and I finally got around to doing it.
The main difficulty with crafting Attachments is that they are often extremely specialized, and do things like add a general purpose scanner, or give penalties like expenditure for Despair/Threat that are hard to actually fit into crafting.
Rather than just having generic Attachments to build upon (something I do plan on adding), I figured I'd take the statted attachments and trim them down for crafting. So Price/Rarity reduction, dropping mod options, adding Advantage, Triumph, Threat, and Despair tables, adding difficulties and timings.
It's still a work in progress, but I wanted some feedback. The spreadsheet includes a bunch of other crafting tables because I want to add my own custom ones (I've done a little bit of that already), but the Attachments are all at the back. I've only finished with the Ranged Weapon attachments, but what do you think?
As for balancing concerns, individual concerns for specific things (i.e. Make Vicious 3a instead of 2a) is fine, but I don't care about the general "crafting is overpowered" worries.