An hammer is available (along with a tomato) at the entrance of cyseal just before the orc ship lands.
Still I do agree the crafting design is deeply flawed.
Common item such as nine inch nails are actually as rare as ruby.
80% of the crafting recipe are not in any recipe book. The developers probably intended us to experiment ourselves but we have no way to keep track of the discovered recipe in game and most of the recipe makes no sense (tooth + knife = electrical arrowhead???) while some which make sense are not implemented (why can't I craft a dagger/metal scrap from an iron bar?)
