You are trained in a craft, trade, or art, such as
Like Knowledge, Perform, and Profession, craft is actually a number of seperate skills. For instance, you could have the skill Craft (carpentry). Your ranks in that skill don't affect any Craft (pottery) or Craft (leatherworking) checks you might make. YOu could have seperate craft skills, each with its own ranks, each purchased as a seperate skill (page 80).
All Craft Checks require Artisan's tools to give the best chance of success. If improvised tools are used the check is made at +2 circumstance penalty. On the otherhand, masterwork artisan's tools provide a +2 circumstance bonus on the check. Alchemist need an alchemy lab, while a fully equiped lab while provide a +2 cicumstance bonus.
To determine how much time and money it takes to make an item, follow these steps.
1. Find the price on the item
2. Find the DC of the item
3. Pay 1/3 the cost in raw materials
4. Make an appropriate Craft Check representing one week's work
If the check succeeds, multiply your check result by the DC. If the result x the DC equals the price of the item in sp (divided by 10), then you have completed the item. (If the result x the DC equals double or triple the price of the item in silver pieces, then you've completed the task in 1/2 or 1/3 of the time. If the result x the DC doesn't equal the price, then it represents the progress you've made this week. Record the result and make a new craft check for the next week. Each week, you make more progress until your total reaches the price of the item in silver pieces.
If you fail a check by 4 or less, you make no progress this week. If you fail by 5 or more, you ruin half the raw materials and have to pay half the original raw material cost again.
You can voluntairly add numbers to the DC to decrease the amount of time necessary to craft.
Armor/Shield Armorsmithing 10+AC Bonus
Masterwork Armor Armorsmithing 20 + original armor
Long/Shortbow Bowmaking 12
Composite Bow Bowmaking 15 + 2x Strength Bonus
Crossbow Weaponsmithing 15
Simple Melee Weaponsmithing 12
Martial Melee Weaponsmithing 15
Exotic Melee Weaponsmithing 18
Mechanical Trap Trapmaking Varies