Where do mods used in crafting come from? Do you get them with the perk like you get the recipe? Or is there some way to get them from scrapping equipment with mods on it?
if you have the recipe you can make them.
You may be able to purchase them. Rarity and maybe faction rep would be determining factors.
I think they can be found as loot.
I don’t think it is in the rules but would be reasonable to remove them.
A reasonable mechanic would be to treat it like adding a mod, so the more on a weapon the harder to remove. For removing multiple mods make separate rolls (at decreasing difficulty). Maybe reduce the difficulty by one (for last mod removed) if you are scrapping the remaining weapon and get half normal materials.