I used copic markers on tracing paper as a rendering overlay.
Initially, I had wanted to use watercolours for rendering my drawings; my choice in paper could withstand the water without wrinkling, but I didn't want to apply it directly over my drawings in case I should make a mistake and ruin the drawing. I tested watercolours on tracing paper to overlay, which created the right effect, but wrinkled the paper a lot. I tested different modes of layering--watercolour on paper with the lines of the drawings overlayed worked most effectively and I almost decided on choosing that for the final submission.
After I found a method in which the watercolours worked well, I wanted to test some other mediums just for fun. I found copic markers on tracing paper created the same effect as watercolours, but didn't wrinkle the paper (being alcohol based) and would blend easier than on paper because the trace didn't absorb it so quickly. This saved me a lot of time since I had already done the drawings on paper.
Perspective lines
Perspective render overlays
West elevation lines
West elevation overlay
North elevation lines
North elevation overlay
Section overlay