Good news that 'parts' will be more common in A19.
Not sure how/if the UI would handle it, but is there any way that we could choose to craft _lower_ Tier items?
Like when you buy high enough Int that you unlock Augers/Chainsaws, but you can only craft the highest Tier, because you're highly spec'd.
Both recent playthroughs I haven't had enough parts to craft an Auger when it got unlocked. I had a few Motor Tool Parts, just not enough for the high Tier.
Just my .02 cents but having an option to 'down-craft' might actually be more of a conundrum than current single option.
Example: this playthrough I was really jonesing for that auger. Think I had 9 parts but needed 12(?). Finally looted a green chainsaw. No-brainer, scrap it & make an auger.
If the option had existed to craft a lower tier, I likely would have done so, then would have regretted it upon looting that green chainsaw...

out:
Would also add a wee bit of 'non-critical' complexity. Say you have 18 Steel Tool Parts & have spec'd to make blues; which take 15 parts(?).
Some might decide to down-craft two greens at 9 parts each(?) instead of the one blue, since one of those greens might have high enough stats to be 'better'.