Here's some ideas for skills and some things that can be added to crafting

Gunsmithing-
A skill that determines one's ability to craft guns effectively. Every craftable gun has a stat "range", and your chances of getting a high grade version of a gun depend on how high this skill is.

Blacksmithing-
A skill that comes into play when crafting things out of metals. Also determines the damage crafted melees can do.

Knapping-
A skill for, well, knapping. Put two rocks, such as obsidian, together, and out comes a sharpened version. How sharp depends on your skill. Sharper rocks mean better damage for certain melees with them in the crafting recipe.

Woodworking/ Whittling-
Determines how well you can make things out of wood. Can affect the amount of available craftable furniture, and acts like gunsmithing for bows, crossbows, etc.

Black Magic-
A skill that determines one's ability to create weapons imbued with dark magical effects. You can generate dark mana (somehow, idk how it could be done optimally) and craft it together with a melee or certain other weapons to apply effects such as extra damage, damage over time, slowing effects, and for some weapons like staffs or items like totems, powerful projectiles.  

Nice ideas  

And of course I should mention this is all assuming that crafted guns, melees and furniture are tradable.