I collect measuring tools and instruments. If it has a scale on it, then I am interested. I particularly like zig-zag rules; long, large rules such as wallpaper, extension, surveying, and glazier's; oddball stuff; and tape measures. I also collect wallpaper tools because my grandfather hung wallpaper during the depression and my Dad gave me his tools. I have very minor collections of tools/items with the name Harper (my last name) and tools patented on my birthday (Jan. 24).
I have a very extensive collection of old tool and related catalogs and books that I use for the tool selling business.
As far as that goes, I will buy and sell any kind of tool and do not specialize. I am trying to get away from the awkward, long, big, heavy, and clunky stuff because it is hard to deal with and hard to sell anymore. Also, I am starting a regular job soon, so I will have to scale down on the tool selling.