relative clauses (please help)?

Hello,

Would you please have look at these relative clauses nd tell me which ones are correct and which ones are incorrect?

a) The leather (that/which) we make the jackets with is expensive.

1. The leather with which we make the jackets is expensive.

2. The leather, with which we make the jackets, is expensive.

3. The leather that we make the jackets with is expensive.

4. The leather, that we make the jackets with, is expensive.

b) The leather is the material (that/which) we made the jackets with.

5. The leather is the material with which we made the jackets.

6. The leather is the material that we made the jackets with.

7. The material that we made the jackets with is leather.

c) The leather that is the material (that/which) we made the jackets with is expensive.

8. The leather, that is the material with which we made the jackets, is expensive.

9. The leather that is the material with which we made the jackets is expensive.

10. The leather, which is the material we made the jackets with, is expensive.

11. The leather which is the material we made the jackets with is expensive.

12. The leather, that is the material that we made the jackets with, is expensive.

13. The leather that is the material that we made the jackets with is expensive.

Thank you