Crafting in Witcher 3 is pretty similar to other RPGs. Creating new item can take, depending on its type, from few mouse clicks to few hours. Below you will find a list of most important aspects of crafting that hasn't been explained well enough in the tutorial windows.
Crafting is a process that consists of few steps. First you must obtain the proper diagrams that will allow you to create new weapons, armor parts and other physical objects. Diagrams can be obtained in various ways - you can find them in the game world, receive them as rewards for completing quests or participating in treasure hunting, or buy them from chosen merchants. You should think before deciding on the latter because diagrams are usually very expensive and Geralt should buy only the ones that will be useful for him.
After obtaining a diagram you must check what crafting materials are required to create the item related to it. Finding the materials is similar to finding the diagrams - you can find them, receive from NPCs or buy at merchants. Another way to obtain the materials is decomposing inventory items like weak swords, items dropped by defeated monsters or candlesticks at craftsman. The game will always inform you what materials you can obtain by decomposing an item. You should do it wisely because you can lose much if you destroy a good item that you could have used yourself or sell with great profit.
Important! If you lack materials to create the item you wanted, you don't have to look for it around the game world or check the offer of various merchants in order to get it. Sometimes all you need to do is decompose some items from your inventory. For example, by "decomposing" more rare harpy feathers, you can obtain regular feathers.
When you have both the diagram and crafting materials you can visit the craftsman and check whether he is able to create the item you want (blacksmisths specialize in sword production, armorers in armor parts production). The game might hamper the process in two ways. First, you must pay the craftsman for preparing the item. In case of good weapons and armors it might cost even few hundred crowns. Second, the craftsman must be on high enough skill level. Information about the whereabouts of the best blacksmith (swords) and best armorer (armors) can be found on the next page of this chapter.
Important! Before making decision of crafting new item check two additional things. First, if the item you will make is better than the one you have currently. For example, whether the new sword deals more damage than the previous one. Second, what are the character level requirements of the item. There is no reason to create an armor for character on 10 level while Geralt remains on level 5. The item created will only waste the space in witcher's inventory while waiting for you to level up.
Crafting isn't used only for creating new items but for upgrading the ones you already have as well. Some swords and armor parts have active slots for items. You can place runestones in swords and glyphs in armors. Each runestone and glyph has specific properties. For example, it can add a percentage chance of causing bleeding on an enemy or it can increase the effectiveness of a specific witcher sign. Runestones and glyphs have various types that differ in quality. Be especially cautious with the best ones and place them only in weapons and armors that will serve you for a long time. You can't simply remove a glyph or rune from the slots, you can only destroy them at blacksmiths to make some space for better upgrades.
Important! Glyphs and runestones can be inserted without the help of craftsmen. You must only select an upgrade from the inventory and then a slot in which it should be placed.