doc wrote:
I have need of an old tool called a 3 cornered scaper. It is at first
sight, similar to a triangular file, with no teeth. Does anybody know
of a place in the UK where one can be purchased? Or failing that, I
was informed that such an implement can be manufactured from an
afformentioned triangular file, with the teeth ground off it by a
grinding wheel, and three fine edges left on it. Does anyone have any
experience of this.

You cam make one from a three-cornered file.
It takes some time and patience.
I have several but the best one is made by grinding one side in a curve.
This curve meets the two other (straight) sides in a point.
This makes a much more versatile tool.

Ken.