Starting with your cylinders around arbitrary minor axes, your work here is quite well done. You're drawing your ellipses with confidence, so as to maintain confident, smooth shapes (though be sure to draw through them two full times, there are a lot of spots where you fall short of that). You're also very attentive to identifying the alignment of your ellipses, with those blue minor axis lines. You catch both more notable deviations, as well as a lot of the subtler ones where you're only off by a little. This is good, as it'll help you avoid plateauing as you get into the "close enough" range.

There are a couple points I want to call to your attention though, just to keep you growing and improving. The first of these is a case that doesn't come up too much in your work, but that is definitely important. If you look at cylinder 100 on this page, this cylinder looks a bit wonky - though it might not be immediately clear as to why this is.

Actually there's part of it that might be more obvious - the farther end has a narrower degree than the end closer to the viewer, which we know from the principles introduced in Lesson 1 would be wrong. The farther end should be wider. But, if we simply made it a little wider than the closer end, that still would not be correct.

In effect, foreshortening manifests in two ways which we can see in our cylinders, specifically in the way the ellipses change from one end to the other. There's the shift in scale, where due to the convergence of the side edges, the far end becomes smaller in its overall scale. Then there's the shift in degree, where the far end gets wider than the closer one. Both of these visual signs convey to the viewer that there is length to this form that does not exist right there on the page for us to see plainly - rather, that part of the length exists in the unseen dimension of "depth", and that cylinder is longer than what we see right in front of us.

Being that they represent the same thing - both the shift in scale and the shift in degree - this means that we do need these to occur at roughly the same rate. If you have a dramatic shift in scale, as we see in 100 (because that far end is much smaller than the closer one), we should also see a more dramatic shift in degree - so that far end should be significantly wider, in order to maintain a consistent impression.

Taking that a bit farther, we also should avoid situations like number 65 on this page, where the side edges remain entirely parallel to one another, giving us no actual convergence, and thus no scale shift from one end to the other. This can happen, but only in a specific circumstance, where the cylinder we're drawing is specifically aligned such that it runs perpendicularly to the viewer's angle of sight, not slanting at all through the depth of the scene, resulting in all of the length we see on the page being all that there is. This results in that vanishing point being at infinity, in the manner discussed back in Lesson 1.

Of course, given that this challenge has us rotating our cylinders arbitrarily in space, we can pretty much guarantee that the alignment will never be quite so perfect, and so we should always incorporate some convergence when doing this challenge, even if only slightly. And you did, for the most part - I'm really just nitpicking on one instance. To be clear, your work throughout this part is very well done.

Carrying onto your cylinders in boxes, you have similarly done a good job here as well. 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.

There's just one thing to keep an eye on - if you look at 207 on this page, here the box's proportions end up far enough away from having the planes containing ellipses be interpreted as square. In such circumstances, students often end up totally misidentifying the minor axis, drawing it as though it is still running down the length of the cylinder, when in fact it aligns more closely to the green/teal lines going up and to the right. In such circumstances, it helps to be more attentive to the ellipse itself, and try to ignore all of the other lines present, so you can identify what's true without distraction.

So! I'll go ahead and mark this challenge as complete.