One-off

[keats]

Who are we to argue with history?

This began as a British expression but is now widely known in the US and elsewhere.
It comes out of manufacturing, in which off has long been used to mark a number of items to be produced of one kind: 20-off, 500-off. This seems to have begun in foundry work, or a similar trade, in which items were cast off a mould or from a pattern (“We’ll have 20 off that pattern and 500 off that other one”.) An example is in a book of 1947 by James Crowther and Richard Whiddington, Science at War: “Manufacturers found it very difficult to give up mass production, in order to make the 200 or so sets ‘off’.”
A one-off was just a single item, used in particular to refer to a prototype. The first known example appeared in the Proceedings of the Institute of British Foundrymen in 1934: “A splendid one-off pattern can be swept up in very little time.” (The reference is to a casting mould formed in sand.)

[Bob Pacey]

Yeah Keats found this little bit when searching mght be of interest.

The off in one-off does not, in fact, stem from some corruption of the word of. Rather, this British usage of off typically appears with a number to indicate a quantity of items produced in some manufacturing process. The Oxford English Dictionary, Safire notes, takes this back to a 1934 quotation from the Proceedings of the Institute of British Foundrymen: "A splendid one-off pattern can be swept up in a very little time." Other numbers can fit the bill, as in the O.E.D.'s 1973 example of an advertisement for "Kienzle printers, 6 off, surplus to manufacturing requirements."

Cheers Bob

[Kym]

Ooohhh, so there IS a PROPER reason! Thanks fellas! I can see it being appropriate in that situation, but I still think my Texas Longhorn farmstay is one of a kind ... I know, I know, I can wah on as long as I want about it, nothing's going to change, it's already in print!!!

Have a great day everyone ....

[Zondrae]

Just for the record.

My husband is a Moulder by trade. His work was so good he was raised to artisan standard and made memorial gates etc. Gosh, is this a blast from the past. He quit that trade in 1974.

[Maureen K Clifford]

so Zondrae - was Wayne a run off?