While studying model building at Bemidji State University, I created this study model entirely out of corrugated cardboard. This was primarily an exercise in creating complex geometry quickly, using crude materials. I ended up using a felt tip pen to draw in the canopies around the gun turrets and the cockpit. For presentation purposes, I also made a cardboard stand and placard (not shown).
This example was actually too detailed, and went beyond the expectations of the assignment.
Pencil is still my favorite medium. This is a quick portrait I did on regular copy paper. I only spent an hour on it, but it's still one of my better pieces.