Starting with your cylinders around arbitrary minor axes, great work! You've included an excellent variety of different orientations and rates of foreshortening, and you've taken considerable care in executing each one. I'm also pleased to see that you've been quite fastidious in checking your minor axis alignments, identifying even fairly small deviations.

There are two main points of critique I want to call out for this part of the exercise:

  • Firstly, your execution of your ellipses does appear to be a little on the hesitant side - you're definitely focusing a bit too much on accuracy and on maintaining a very tight ellipse, and in so doing you're sacrificing the confidence of your stroke. Remember to apply the ghosting method (whose last step is all about a confident execution regardless of accuracy), to engage your whole arm from the shoulder, and to draw through each ellipse two full times before lifting your pen. While you're doing all three of these to a point, I feel that there are cases where one or two of those points may need more attention in order to maintain as even a shape on your ellipses as possible.

  • As we rotate a form like a cylinder around in space, we see two distinct shifts in the ellipses at its ends. One shift is of overall scale, where the far end will be smaller than the end closer to the viewer, due to the convergence of its side edges. The other is a shift in degree, where the far end widens proportionally relative to the end closer to the viewer. The key point to keep in mind is that both of these shifts occur in tandem - when one shift increases, so too should the other. Now, when we look at some of the more dramatically foreshortened cylinders in your set, we can see that you tend to apply that scale shift more readily, while the shift in degree lags behind. If you look at those on this page for instance (specifically 83, 86, 88, etc) it does feel a bit off, as though the far end should be wider than it is. You do have some that are more correct though, like 85, 87 and 90. You just need to be more mindful of keeping the shifts consistent with one another.

Continuing onto your cylinders in boxes, I think you've done a great job here. This exercise is all about helping students sharpen their instincts when it comes to constructing boxes which feature two opposite faces which are proportionally square - regardless of how those boxes are rotated in space. Instead of having one memorize all the math needed to understand how to construct such a box, we instead employ the same tactics as in the box challenge, where we used line extensions to develop your instincts towards consistent convergences.

By adding the three lines for each ellipse (the minor axis and two contact point lines) and testing how far off they are from converging towards the box's own implied vanishing points, we can test how far off we are from having ellipses that represent circles in 3D space, and therefore planes that enclose them which represent squares.

In this regard you've done quite well, save for one little issue that may have held you back a little. Here, instead of extending the minor axis lines all the way back, you confused it with the other cylinder exercise. Extending them further back helps us identify more easily when they're not aligning to the box's vanishing point, and by how much, allowing us to make a more useful analysis.

Anyway, just be sure to keep that in mind when doing this exercise in the future. All things considered, you've still shown considerable progress here, and you are certainly ready to move on. I'll go ahead and mark this challenge as complete.