Outlining a shape-changed object in Inkscape

This page explains how to get an outline of a join-/cap-shape changed object using Inkscape.

Let's make an object from which we are going to get an outline.

Set the shape of the join and cap of the object. Change line width too.

Then, you'll get an object like this. Let's get an outline of this object.

Put an object inside the triangle. Call this object a dummy object.

Then, select the two objects (triangle and square) and select "Path" > "Division"

Divided objects look like this.

Select only the triangle object.

And select "Path" > "Stroke to Path"

Then, you get the outline and inline paths

Select this object

Clear the fill color and

Set the line color.

Remove the dummy object (square object)

Remove paths inside the object. You will get the outline of the object.