There exist two books titled Do It Yourself one of which appears in The Witcher 2: Assassins of Kings, and the other in The Witcher 3: Wild Hunt.

The Witcher 2: Assassins of Kings Edit

Witchers can enhance their weaponry through crafting. Crafting an item - be it a sword, armor, armor enhancement or a rune to be branded on a blade - requires a diagram and the components it lists. Diagrams can be bought from merchants or obtained as a reward from appreciative employers. Components can be cut from the corpses of defeated foes, though some may also be found lying around among everyday items. Having collected all the necessary elements, a witcher must find and pay a craftsman to produce a given item in his workshop.

The Witcher 3: Wild Hunt Edit

How many times have you cursed a tailor for sewing a shirt more crooked than that infamous home in Novigrad? How many times have you argued with a smith who proved unable to forge a simple horseshoe in a month? How many times will you steal food from your children's mouths because some armorer demands a Koviri fortune for a ho-hum helmet? Enough! Basta, I say - and so should you! Empowered by the tome you hold in your hands and a few simple tools, you shall be able to perform basic repairs all by yourself, and perhaps even create something from scratch. So show those extortioners from the crafting guilds who shall make the fool of whom, roll up your sleeves and get to work!