May have been tough, but you did a great job! Starting with your cylinders around arbitrary minor axes, you've really knocked these out of the park. Your ellipses are drawn confidently, your side edges are straight and smooth, you've experimented a great deal with foreshortening (something that a lot of people seem to forget to do, despite it being in bold in the assignment section), and in general you're doing a great job of establishing your understanding of how the way in which these forms changes based on how they're oriented in space.

One point in particular that I try to keep an eye on - which is the main reason I ask for varied foreshortening - comes down to the two ways in which foreshortening manifests in our forms. It does so through both the shift in scale from one end to the other (where the farther end is overall, smaller than the end closer to the viewer), and the shift in degree where the far end gets wider. The thing that some students understand on a gut-feeling level, but not necessarily consciously, and others don't quite grasp on their own, is the idea that these shifts occur in tandem, since they're both representative of the same thing.

If we were to see a dramatic shift in degree, yet a minimal shift in scale, then that tells the viewer two contradictory things: that the length of the cylinder exists predominantly in the "unseen" dimension of depth, and that the length visible on the page is all that there is. These two statements cannot both be true - and thus, we must ensure that the two shifts occur together, both either being more dramatic, or both being more shallow.

As a whole, you seem to understand this - if not consciously, then subconsciously, in which case hopefully my explanation will have pushed it into your conscious mind.

Continuing onto the cylinders in boxes, you're doing a similarly excellent job. This exercise is really all about helping develop students' understanding of how to construct boxes which feature two opposite faces which are proportionally square, regardless of how the form is oriented in space. We do this not by memorizing every possible configuration, but rather by continuing to develop your subconscious understanding of space through repetition, and through analysis (by way of the line extensions).

Where the box challenge's line extensions helped to develop a stronger sense of how to achieve more consistent convergences in our lines, here we add three more lines for each ellipse: the minor axis, and the two contact point lines. In checking how far off these are from converging towards the box's own vanishing points, we can see how far off we were from having the ellipse represent a circle in 3D space, and in turn how far off we were from having the plane that encloses it from representing a square.

In doing a very effective job of applying all of these line extensions correctly (if with somewhat faded ink) you've developed those instincts towards proportion quite well - honestly, the consistency of those convergences towards the end is quite remarkable. Your grasp of how to proportion your boxes regardless of how they're oriented in space will no doubt be extremely useful as you move on into the next lesson.

So! I'll go ahead and mark this one as complete. Keep up the great work!