I have just bought and used, for the first and last time, a special 35mm cutter designed to cut the holes in a kitchen cabinet door for their hinges. This tool joins a select collection of tools used only once in my life, and theirs, to fulfil a vital role that I can't consider throwing out or selling.
The very long nosed circlip pliers used once in a gearbox rebuild, the right-angled ratchet screwdriver used once when stripping an engine etc.
I don't count jigs or tools I have made – I can get rid of them without a second thought but as for the bought ones, even after 40 years – I just might need one of them again
How many do you have?
Tony