Starting with your cylinders around arbitrary minor axes, your work here is looking good. You've done a great job of working in a fair bit of variety in terms of the foreshortening, which is very nice to see. This is particularly useful to me, because it shows that you understand the relationship between the shift in the overall scale of one end of the cylinder compared to the other, as well as the shift in the degree. That is, the far end is smaller overall, but wider, than the end closer to the viewer.

The key point here is that these two "shifts" occur in tandem, and your work reflects this. You have circumstances where the far end is much smaller and much wider, or just a little smaller and a little wider, with both of these qualities suggesting a lot of foreshortening (and therefore a longer cylinder than we can see on the page) or very little foreshortening. Often times students who don't understand that these two shifts work together will have cases where one shifts dramatically, but the other more minimally, leading to a visual contradiction on the page.

Beyond that, it seems you're doing a good job of checking your ellipses' alignments, and while your improvement on this front isn't terribly obvious, that would be because you're already doing a really good job of it. There are a few outliers that stand out as being more notably off, but in most cases you're quite close.

Moving onto your cylinders in boxes, I can see that some of the boxes got pretty rough, and you do have a tendency to have those that are longer to have their sets of lines converging in pairs (instead of all 4 at once), but this is a pretty common issue. It comes down to just being more aware of the issue and to specifically compensate for it, making the convergences steeper when you know that far end is going to be farther away.

As far as the core focus of the challenge goes, you're doing great. You're checking your line extensions well, and you're applying the analysis into every subsequent cylinder. What this does is it develops your ability to construct boxes that specifically feature two opposite faces which are proportionally square.

After all, checking how far off the ellipse's line extensions are from converging towards the box's own vanishing points, and then doing what we can to bring them closer, means we're checking how far off we are from having those ellipses represent circles in 3D space. And when the ellipses do represent circles in 3D space, then planes that enclose them in turn represent squares in 3D space.

Developing a more intuitive sense of this - as you have here - is something that will come in quite handy in the next lesson.

So, I'll go ahead and mark this challenge as complete. All in all you've done a great job.