This isn't so much a implemented rule in my games as something I was thinking about.
I don't want to get too in-depth about my game but basically I made it so crafting is a viable option that almost everybody can do without losing any adventuring time.
I was thinking, should crafting an item give a small amount of XP? (I like using an XP Leveling system) and on-top of that if I do choose to do that.. Should that XP go towards the overall Character level or.. Into a separate Crafting Level.
For example: Level 10 Barb crafts a sword, the sword gives say... 100 XP.
That XP would either go into the character level or a "crafting level" such as Crafting level 1 - 0/200 XP and each time crafting levels up you gain 1 Misc. Mod. to that craft.
Let me know if this sounds like a good idea or not or if it's already been done and I just haven't seen it.
Oh that's a problem that might eat up a bit. I remember how in D&D (at least 3.0) it still COSTED xp to actually craft something..meaning commoners shouldn't be able to carve a spoon out of wood before they kill something.
Most sense it would be to separate the crafting xp from class xp. That way you don't run into situations where you learn new technique of painting on canvas by beheading goblins..or even worse - learn how to shoot a fly from a mile away by beating a piece of metal into shape.
Then again - it seems all D&D based systems make assumptions that progress (and quite often crafting - so as not bog down adventure time) actually takes place when you're not out in the action field, analysing what you've learned in the meantime, but not discovering anything new. Many people bothered by that.
I have players who are annoyed at how much it costs to craft magic items. Then again, they're used to the Soul Gem approach in Skyrim - at least, until I told them that it's more akin to Morrowwind where you'd need a really expensive Soul Gem with a powerful entity trapped within to enchant something good. ;)