Shading without a pencil

Not only have I realised that I do not know how to use any other medium other than a pencil. Here are my trials and tribulations. My first homework asignment, shapes in two point perspective. The lines are light, so you can only see the shapes, which are done in ink. It would be nice, he said, if they were shaded (to show depth). I'm at a loss. I don't know if it's just because it's late and I've been staring at this for a long time, but I think not. I need to fix my pyramid ..and cylinder, and figure out what to do with my sphere.. : (


1,2 shapes
3,4 learning to use a marker.




It's good to note that this homework asignment is not for marks. I think. But still....