Is it possible in three js to outline the edges of shapes in three.js?

Question

I have the following 3d scene generated, with square "timber". I would like to add outlines to the shapes, but not show the triangles that make up the rectangles. Is that possible? I am also addind side walls, made out of different planks, but the problem is it looks like 1 big rectangle, instead of multiple planks. That's why I would like to show the outline of the rectangle, but don't want to show the triangles. I would like to do cartoon like lines.

Answer 1

Based on the answer provided by Prisoner849. I can now build my model with clear lines.