An 1880/1890 sewing machine that my grandmother inherited, not sure from whom, I use it to lockstitch thick layers of leather and leather like material that my normal (electric) sewing machine can't handle. I found a box of needles for it at a junk sale a while back for a good price, I modify them a little bit with a dremel to turn them in to leather optimized needles.

If I don't count books and decorate objects, my second oldest item that I activly use is a brownie box model 2b analog camera from 1917/1920, incredibly simple and cheap made design, nothing that can break on it. It was the first mass available camera at the time costing only 4$ film is still available pretty much everywhere and with advances in film it works better than it did in the day.