This is the first Cross-section I have ever done. It was based off of a simple 5 minute sketch for which the life of me I cannot locate anymore, but I'll run across it eventually. Anyway I approached this work first doing the rough lines in blue graphite and dark graphite and then inked the image which you see with blue and black micron pens. Not bad for a first attempt- there are definitely errors, but that can be the glory of o.c.d. detailing- the viewer can't see those errors. I love that trick.