And here is where we reach the "Hump Day" section of my assignment, where I was dragging myself to reach and pass the halfway point. I counted on my love for Sam and Dean to fuel me when I wanted to just give up and sketch 50 rocks or something instead, and the brothers did not let me down. I fear my wearniness for the assingment may have shown in my work here (one of them, IMO, doesn't even look like Dean), but I leave that for you to judge.
Here's drawings
1-10, and
11-20.
21
22
23
24
25
26
27
28
29
30