Starting with your cylinders around arbitrary minor axes, you're hitting most of the notes I'm looking for here. Your ellipses are confidently drawn, using the ghosting method and from your shoulder, and you're fastidious in checking the true alignments of your ellipses, and learning from that analysis. You've also included a good bit of variety to your foreshortening and orientations, so there's a lot of good experimentation going on here.

One thing I do want to call out is just something I like to keep an eye out for. When we play with more dramatic foreshortening, certain discrepancies can show themselves more easily. You're obviously aware of how the ellipses' degree and scale both shift as we move towards or away from the viewer, but one thing you may be missing, is that the two shifts must occur in tandem. That is, to say, at roughly the same rate.

I noticed a few - such as 112, 106, and 97 - where the scale shift is quite dramatic (with the far end getting much smaller), but where the degree shift is fairly minimal. This can make a cylinder feel a little "off", as we're basically telling the viewer that the cylinder is undergoing both "very little" and "quite a lot" of foreshortening at the same time.

Aside from that however, these are looking really good.

Continuing onto your cylinders in boxes, here you're doing a great job. As you well know by this point, the exercise is more focused on the construction and proportion of the boxes, and the cylinders themselves are just a means to test whether the two opposite faces are proportionally square. Throughout this exercise, you've applied that manner of analyzing your results to great effect, and I can see improvement across the set not only in getting the ellipses' lines to converge correctly, but also with the convergences of all your box's edges as well.

Beyond that, there's not really much else to be said. You're doing a great job, and I can see your level of comfort with both boxes and cylinders serving you well into the next lesson. You may consider this challenge complete.