ITEM CRAFTING IN STORM OF ZEHIR
Here is some basic advice reflecting both the new gameplay and item crafting systems in Storm of Zehir.
Recipes
It's simple, if you want to create a certain item or add an enchantment to an existing item, you need to find the recipe for it first, which will be added to the recipe books that are always carried by the main character.
I indicate the locations of what I think are the most important recipes as I make my way through the various sections of the game.
Not All In One Character
In the OC a character needed to have both the needed item crafting feat (e.g. Craft Wondrous Items) and the needed spell to be able to craft a certain item or add a certain enchantment to an existing item.
In SoZ, the requirements don't have to all be supplied by the same character, as long as anybody in the party has one or more of the requirements. For example, for a certain created item or for a certain item enchantment, it is entirely possible for one character to have the needed recipe in the recipe book, a different character to have the needed item crafting feat, and yet a different character to have the needed spell. That means you will enjoy a lot of flexibility in the overall design of your party. As long as you make sure at least someone in the party has the item crafting feats you'll need, and as long as all the party members between them will provide the needed spells, you'll be good to go.
Craft Armor and Craft Weapon
The OC system needed the right armor or weapon mold, and enough of the right type of Ingots, to create an armor or weapon. Ingots and Molds are not used in SoZ. What you need instead is the right recipe, and enough of the right metal as a resource (e.g. Mithral or Adamantine). Acquiring a metal resource for your armor and weapon crafting needs typically involves trading away enough trade bars to a town in exchange for the needed metal resource.
Craft Magic Arms and Armor
To add enchantments to an existing armor or weapon, all you need is the recipe, the Craft Magic Arms and Armor feat, and enough gold. Also, there's a limit of three enchantments for any armor or weapon, even if you reach epic levels during SoZ.
Craft Wondrous Items
Crafting wondrous items is more involved. What you'll typically need is the recipe, the Craft Wondrous Items feat, the right base item, the right creature component, the right gemstone, the right spell, sometimes a resource like Mithral or Adamantine, and enough gold.
Base items to keep an eye out for include:
Critical Hits
I was dismissive of the value of critical hits during the OC because the later stages of the OC become crowded with undead and other critical-immune enemies, and during Mask of the Betrayer because almost everything during that expansion is immune to critical hits.
It is a different story in SoZ, since almost everything in SoZ can be critically hit. That includes the ultimate enemies in the game, the Yuan-ti. So it certainly pays to maximize your chances of critical hits during SoZ.
Furthermore, the concerns about critical hits in the OC and MotB could be minimized by using spells like Keen Weapon and Weapon of Impact only when you knew ahead of time you were going to be faced with enemies who could be critically hit. It's a different story in SoZ, since you can very often be hit with several random encounters on the Overland Map, one after the other, with the probability that any spell buffs you may have cast will expire.
It may therefore be worthwhile to consider adding the Keen Weapon property to a weapon used by at least one of your main warriors. An even better approach may be to have your warriors invest in the Improved Critical feat for their weapons of choice, since that will mean their weapons can hold three other weapon enchantments (i.e. extra damage) besides the Keen Weapon enchantment.
Amulets of Natural Armor
I was also dismissive of using Amulets of Natural Armor during the OC, since I could rely on Elanee or Bishop to use the Barkskin spells. But again, Barkskin spells are likely to expire in the course of multiple Overland Map encounters. It is therefore worthwhile to find and equip Amulets of Natural for at least your main warriors. The benefits will always be there, without the worry of expiring or getting dispelled.
OC Item Crafting
There is a theoretical possibility that you may want to keep in mind. The workbenches in Samargol and in Crossroad Keep can only be used for SoZ crafting recipes.
If you establish trading posts with certain towns in the Sword Coast during Act II (e.g. Leilon, Thundertree), those trading posts will have workbenches that you can place items into and use the OC crafting recipes with. There are, however, significant limitations involved.
There won't be any Leather Hides or metal Ingots available, so you won't be able to use Craft Wondrous Items in OC style. You would be pretty much limited to adding enchantments to armors or weapons.
Note also that the crafting essences available will be quite limited. My observation was that I was limited to Weak Earth Essences from Earth Elementals in Samarach during Act I, Radiant elemental essences from various elementals in the Sword Coast during Act II, and Radiant Power Essences from Elder Earth Elementals in the Dwarven Mine in the northern part of Samarach during Act III. Furthermore, there won't be a Mortar and Pestle available, so you can't downgrade the essences you find into the ones you need.
Lastly, unlike the SoZ recipe system, you need the armor or weapon plus crafting essences in a Magician's Workbench, plus the crafting character has to have both the Craft Magic Arms and Armor feat and the right spell to complete the enchantment. Just like the OC crafting system.
So to summarize, OC style crafting is possible in SoZ, but your options are going to be very limited.