I tested this over the past couple days.
You need 30 tinker skill to make a trapped box. If you have less it tells you that you don't have the necessary skill.
I made a tinker with 31 skill (2% chance to make dart trap) and it took me a long time to trap a box. This box did 8-25 damage against a char with 44 physical resist (120 Resist).
I added a +21 Talisman which raised my chance to make the dart trap to 23%. I made one the very first try. This box did 8-25 damage against the same char.
I then made a char with 10 Tinkering skill (elf) to see if the 21 talisman would enable him to make trapped boxes. I could NOT make them, I got the "necessary skill" message.
So it looks like the real skill in tinkering is what determines the damage of the box and not the adjusted skill from the talisman.
The only thing I didn't look at was if there is a "block" of skill that changes the damage, like 30-60 = x damage, 61-90 = x damage and >90 = x damage. I don't really care about that because I'm trying to make boxes with the lowest damage.
OH and if you make a human char just for this, start with 30 tink (get a tali to help make the boxes) and NO carpentry. The 20 from human makes them at about 70%.
