Matt Fussell has written a small tutorial, How to Draw in One Point Perspective, and the idea of making a cube enticed me to try. The theory asks for a large square and a smaller one inside it. The two are to be connected by “orthogonal” lines that go from the corners toward the horizon where they gather in one point. The line segments that extend out and away from the two shapes have become unnecessary and must be erased. That is where I had a problem, how do you erase without an eraser tool? I had drawn a number of boxes with the line tool. That was a wrong choice; I tried the curve tool, did an edit and, with the help of nodes, finally was able to cut away the unwanted segments.