In the workshop with Bobbin Boy! The three-cornered tool

The three-cornered tool. These tremendously useful little tools can be used for so many turning tasks. The pyramid need not be "balanced" in size, and, in fact, the tool is most useful if each of the three sides is slightly different, as this gives you three cutting edges at various angles.
A video showing this tool, made of a screwdriver, in use is here, / 607413820871285