Locksmithing

This is the specialized skill of making locks. It is treated like other "craft" proficiencies when checking for success. Also, thieves with this proficiency gain a 10% bonus to their lockpicking skill, because they are intimately familiar with the internal structure and working of so many locks.

Besides Troubleshooters, dwarf and gnome thieves of any kit can take the locksmithing proficiency to fill one slot at no cost, because of the tradition of craftsmanship and mechanical things in their cultural heritages.

[Complete Thief's Handbook]