A man's arm. After finishing the contour line drawing, I left it alone for about a week. When I came back to it, I immediately noticed some suddenly blatant errors in the wrist portion which I was able to correct before settling down to shading. It sure saved me the frustration of getting near the end of the shading process, standing back, and grimacing at a newly glaring mistake! However, as a good friend recently chastised me, the point of doing the Bargue course is to learn and get better with each plate, not to get each one perfect at first go.