Bill Houghton, Sebastopol, CA
I think tinkers were not a guild trade; more like itinerant handyfolk who could fix kitchen implements, including tinware. This is not entirely supported by the online references I found; but the itinerant repair person was a definite fixture of the 18th/19th century.

I think tinner was a recognized trade, another way of saying "tinsmith." The online dictionary says it's also another term for tin miner, which could get confusing. But I've never seen that reference; I've only seen it used for tinsmiths. Tinsmiths seem to be distinguished from sheet metal workers by what they made: tinsmiths seem to have made mainly kitchen and household items, often from tinned steel (thus the name), while sheet metal workers worked a broader range of things, and often to larger (thicker) gauges than tinsmiths.

Thinner, on the other hand, is either a term for a solvent used for paint and the like; or a goal for many of us (I certainly want to be thinner).