This was an exercise in drawing a range of body types from memory as opposed to using reference. I found this task both challenging and immensely enjoyable. It has been very successful in highlighting my strengths and weaknesses in terms of both style and anatomical knowledge.
how to draw
how to draw abs. http://kelpls.tumblr.com/post/72186004376/im-sorry-to-ask-but-i-was-wondering-if-you-may-show-us
viria tutorial - Google Search
Nautilus print -- this image was drawn by hand, using formulas, rulers and protractors to create the shell shape.
Male anatomy reference *Source: http://epicwallcz.blogspot.com/ (https://shorte.st/es/ref/f3865e4100)