OK, I was chewing this over at lunch (Mmmm: pepperoni Artificer!

).
The Artificer is pretty much 3 things:
1) A spellcaster,
2) A magic item crafter, and
3) A guy who gets "other stuff"
1) The Artificer as Spellcaster
At heart the Artificer is a wizard with the advantage of casting any spell he knows without memorization, while wearing armor, with a more robust hit-die and superior attack progression than the base wizard. This is balanced out by the fact that his list of spells is restricted, his casting times are prohibitive, and he has fewer available spells per day compared to normal spellcasters.
I would say that portion of the Artificer is fairly self balancing. Although lessening some of those restrictions might help boost the character up to "Pathfinder Class" shape later on, let's put that aside for now.
2) The Artificer as Craftsman
As Remathilis points out, this is the part that gets gimped by the changes in the PRPG. If the Artificer's going to keep this as part of his schtick, we need to address these issues, and add to his capabilities to give him an edge over other crafters.
Spellcraft is the universal skill that is used to make magic items. The DC is 5+ caster level. The artificer used use magic device at DC 20 + caster level to accomplish the same trick.
Here we can just have them default to the standard crafting rules. In order to help them maintain their edge, perhaps grant a +1/2 Artificer level bonus to Spellcraft when crafting items.
Artificers can emulate pre-reqs (except item creation feats) they don't normally meet with a use magic device check (DC 20+CL) per missed pre-req. So can anyone else by adding +5 per missed pre-req to the spellcraft DC.
Once again use the standard rules, and again give a +1/2 Artificer level bonus to UMD checks when crafting items.
Pathfinder artisans can make items while adventuring (only netting 1/2 the benefit of time) thus eliminating the artificer advantage on time.
To maintain the Artificer edge, we need to give them an ability that decreases their required crafting time. I think this plays nicely with the next point, so see below.
Artificers gained a craft-reserve of "XP" to spend on items. No longer needed.
The point of the craft reserve is to decrease costs, and we can carry that over to a savings on the gp costs. I think the solution here is to provide incremental reductions in both time and cost, spread out over the Artificer's level progression.
The question is: What should the savings be? At the moment I'm leading to 25% off gp costs at 5th level, 50% off costs at 10th level, and 75% off as the capstone 20th level ability. Not sure on what to do for the time reduction, but perhaps scaling up 20% every three levels? Need to see where the holes in the ability progression fall.
5th level artificers gained retain essence, which let you recycle XP from items. No longer needed.
This can also be converted to a gp-based ability. I suggest a 20% recovery of "essence" that can only be used to create items or pay for spell-related xp costs.
Artificers get "Artificer knowledge" which let them identify magic items with an special level+int check and one minute. Spellcasters can cast detect magic at-will and identify items with a spellcraft check.
Artificers should now, at will, be able to make spellcraft rolls to identify magic items as if they had cast the Detect Magic spell.
Don't want to be spellcaster but still want to make items? Try Master Craftsman
While I don't think this has any impact on the Artificer, I wanted to point out that this is a cool way to make a Magewright as an expert, as opposed to his own NPC class.
3) The Artificer as a guy who gets "other stuff"
So the Artificer also gets: Trapfinding, free-item creation feats, meta-magic item use, a slightly higher (level+2) caster level to make magic items, and a hommoculus. I think all of that can pretty much stay.
So the next question is, how will this class stand up to the Pathfinder core? I think I'll leave that for a later post. Phew, all this class creation is a lot of hard work!
