This was laid out 1st in 2-d. I used rulers to establish vanishing points, one about 8" to the left, and the other about 30 " from the right. I made marks on the desk and taped the drawing down. Rendering, as in scan, was 1st done in pencil, establishing the angles of all the block rows. Verticles were sketched in freehand. A 005 micron was used over the pencil to form the outer shapes and hatching was added for the shadows.
step 2 of 2
Pen work was gradually developed over rough sketch.