A useful skill in the Stone Age and the Late Renaissance, knapping flint allows a craftsman to take raw stone and convert it into useful tools.
For each level of proficiency taken, a knapper can knap two ounces worth of products per day. Two ounces constitutes one knife blade, two spear heads or axe heads, three dozen arrowheads, or one dozen gun flints.
Knapping requires a raw rock, called a core. The number of items that can be crafted from a core varies by weight. One stone of flint can be made into 64 knives, 128 spear heads, 4 axe heads, 2,000 arrowheads, or 500 gun flints if used efficiently. Knappers often end up with wasted material (known as debitage) due to flaws in the stone or errors in technique.
Knapping requires a proficiency check:
Apprentice: 7+ to make items with double normal material, 11+ to make items with normal material.
Journeyman: 3+ to make items with double normal material, 7+ to make items with normal material.
Master: Automatically make with double normal material, 3+ to make items with normal material.
It is recommended that a check be made for a day's production, not for each item.
A second crafter will generally be involved in making the furniture (shaft, handle, rope) to hold the blades made by the knapper. While called gun flints, the last type of flint can be used to craft stone-bladed swords. 8 blades are needed to make a one-handed sword, 16 for a two-handed sword (see macuahuitl for an example of such a weapon).