Shrapp Hamnier
Explorer
Seeing as a tinker is "a person who makes a living by travelling from place to place mending pans and other metal utensils," I'd say they already do have a use - repairing things.
Ok... but what use is that when one has the Mending spell?

Thank you KahlessNestor, though I guess I didn't specify none firearms. Thats already something for the artaficer, and even then I have a small prejudice against guns being in a mideaval setting.
Woot! Thank you Eltab!