We're approaching the Crafting & Enchanting stretch goal, so I thought it'd be a good time to discuss mechanics.
Arcanum, in my humble opinion, had one of the best crafting systems out of cRPGs I have played. For those who haven't played this title, here's a quick recapitulation :
The general concept was simple - characters acquired various item schematics by spending of character points in the appropriate discipline. However, some had to be found - either in shops or in various locations in the game (some would be notoriously hard to locate). It was then simply a matter of finding ingredients to create the desired item :
But here's where it got interesting :
1) Lots of variation
There were eight disciplines (Herbology, Chemistry, Electric, Explosives, Gun Smithy, Mechanical, Therapeutics and Smithy) in the game, with each discipline having seven degrees within it. And that's not counting found schematics.
2) Not limited to equipment upgrades
While some of the disciplines offered just that (i.e. better armour), it was not a general rule. That brings us to the next point.
3) Consumables and utility equipment
That, I feel, was the strongest part of this system. Most of the schematics were of various consumables or other assorted amenities. For an instance, the player could craft :
a) various grenades (stun, flash, fire, acid, smoke etc.),
b) substances that could benefit the player (buffs : combat and non-combat) or harm their foes (poisons),
c) traps,
d) various useful gadgets (better lockpicks, lanterns, projectile reflecting shields, trap detectors etc.),
e) resources (bullets, batteries etc.)
f) even pets (automatons).
In short - all sorts of useful (or somewhat less so) items, with wildly different combat and non-combat applications.
4) Mixed crafting
Some found schematics required having an expertise in two disciplines - e.g. machined plate required advanced knowledge in the fields of Smithy and Mechanical.
I think these concepts would be a good source of inspiration for PE.