To mark International Left Handers Day, which celebrates the “uniqueness and differences” of left handers in a predominantly right-handed world, here is a sequence of six drawings showing how I constructed the interior view of St. Mark’s Episcopal Cathedral I posted a couple of weeks ago. I first established a corner where two adjoining planes meet, and transformed these planes into a volume with the addition of four columns. Then, over this 3D framework, I developed the details on the columns, pews, windows, ceiling patterns, light fixtures, and sanctuary.