I haven't read beyond the first post, so this may have already been noted by someone, but needing to carry a variety of parts with you just so you can repair when you aren't at your base would be a pain. Say you have 3 items plus armor that need repair kits (we won't count vehicles since they don't really have parts). This means you need to carry repair kits and 3 different parts for the items and another stack for armor. That is five stacks of inventory space you lose instead of one for the repair kits. Unless they made a special "bag" for repair kits and parts or increased your inventory space by another row, it just isn't a great option.I like the change in A21 where right now, scrapping any tool or weapon gives just the 1 part and that crafting different Tiers of those determine how many parts is needed. However, once we've crafted whatever we've wanted or needed, there isn't much use for those parts any more beyond just selling them or crafting a spare or something.
To that extent, I was thinking how it could actually be tied in to repairs. Currently repairs in general cost just the 1 repair kit to repair anything fully (vehicles exempted). I was thinking that to perhaps correspond to the different tiers, a part can be used in conjunction with the repair kits. So for example, a Tier 1 pistol would take 1 handgun part and 1 repair kit to repair fully. To correspond, a Tier 6 pistol would then take 6 handgun parts and 6 repair kits to fully repair it (if we use 1 handgun part and 1 repair kit, it could make it usable, but only restore something like 1/6 its durability?).
It would give an incentive to stockpile parts and also make them alot more valuable. Trade off naturally is that its going to make it more challenging in the early to mid game perhaps. Any thoughts?
I haven't read beyond the first post, so this may have already been noted by someone, but needing to carry a variety of parts with you just so you can repair when you aren't at your base would be a pain. Say you have 3 items plus armor that need repair kits (we won't count vehicles since they don't really have parts). This means you need to carry repair kits and 3 different parts for the items and another stack for armor. That is five stacks of inventory space you lose instead of one for the repair kits. Unless they made a special "bag" for repair kits and parts or increased your inventory space by another row, it just isn't a great option.
Besides, there are a lot of things that I don't need late game, or at all, so the fact you don't need the parts isn't really unusual.
I would be fine with repair kits requiring *any* one part to create, though. It would use up parts you don't need without requiring extra inventory space. Of course, the game currently doesn't offer an option to use a choice of items in a recipe.
Up above I suggested having a special item referred to as "Spare parts" you could scrap any one gun or tool part 1:1 at a workbench for them and they would be a third required component for repair kits. So basically what you're suggesting is very possible, you just need an intermediate step. Maybe a different term than Spare Parts? 'Machined parts', seems like it accurately describes the fact that you can't easily remake them and that they're a product of The Before Times?
Is it unrealistic? Well it's not great, but it's sure better than everything being repairable by a lump of iron and a roll of duct tape, even if you very generously assume the iron's been forged into specific shapes and not just an ingot.
There's the issue of vehicles, which must also be repaired, but maybe engines could scrap for 2-4 Machined parts. And you could add machined parts as rare finds in the world where appropriate.
Icon could maybe be mostly fasteners (screws, bolts) and some generic tooled shapes (square block with circular hole, brackets), maybe a small spool of wire, to give them a distinctly different flavour than mechanical parts and an ambiguous position between those and electrical parts.
This was my thought process and something I am probably going to try to implement in A21 in my mod (and return repairing but making it expensive).
Like you stated, have a basic level of the components (for lack of imagination on my part, range weapons components, melee weapons components, armor components, engine components). Then use those parts to either craft repair kits or individual components to start weapon crafting (so they are required to craft for example shotgun parts). You can limit the amounts of different repair kits by breaking them up into a few - say have a repair kit for weapons, tools, and armor and requires the components of each to craft up, then a different one for vehicles that requires vehicle elements like engine components, oil, plastics, etc.
FYI, in my mod from A20 that I am slowly porting over to A21, I had already changed how engines worked in it. I change the engine drops to engine parts (and easy to do since I just use the parts master icon with the engine icon to give it the parts symbol in the corner) so then you had to craft it either into a small engine for certain recipes or a larger engine for other items.