All in all, pretty good work! You've certainly been very conscientious in applying the line extensions and minor axis check lines throughout this set, and you've worked to learn from your mistakes and gradually improve over time. As a whole, the challenge has been completed quite well, but there are a few things I'd like to point out. Some of them are little hiccups/mistakes, and some are things that were left for students to perhaps discover on their own as they work through the task.

The first thing is one of these things you seem to be aware of, but maybe not enough to necessarily be fully conscious of it. It comes down to the relationship between the scale shift from one end of the cylinder to the other (basic foreshortening, near end is bigger than the far end) and the degree shift from one to the other (closer end always has a narrower degree than the far end). The main point I'm seeing if students will pick up on themselves is that both of these properties are tied to the foreshortening being applied to the cylinder - the more dramatic the foreshortening, the more dramatically both will shift. Conversely, if the foreshortening is shallow, only minimal shift will be seen both in scale and degree.

The key thing to keep in mind with this is that it also means you'll never see a situation with a dramatic degree shift (where the far end is WAY wider) but minimal scale shift (where the far end is only slightly smaller than the near end). Looking at your cylinders, you do appear to at least be somewhat intuitively aware of this, which is good to see.

Next, moving onto your cylinders in boxes, one important point to raise about this section is that I have sneakily assigned an exercise designed to make you practice your boxes, by making you think you were practicing cylinders. In fact, this exercise is largely intended to teach you how to build boxes that feature opposing faces that are proportionally square (the ones that'll contain your ellipses). The cylinder itself becomes another correction/analysis technique (just like extending parallel lines) that allows us to test whether or not the faces are square, or how far off they are. After all, if the face is not a square in 3D space, then the ellipse it contains would not be a circle, and therefore the contact points/minor axis alignment would be off.

To that point, I did notice that you purposely seemed to make a point of drawing your ellipses in such a way that forcibly corrected this after the fact... which admittedly isn't bad, and certainly does get you some work in on estimating the proper degree of an ellipse to make it properly circular, but in this case I'd still push you to just draw the ellipse filling the face of the box entirely. Reason being, when you're actually laying out boxes as part of a construction, choosing to change things halfway through will undermine the general principles of construction (where we adhere to the choices and decisions made in earlier steps).

The third and final thing I wanted to point out was that as you get into longer boxes, a lot of people get into an issue where they tend more to have their lines converging in pairs (near end's edges converge together, and the far end's edges converge together, but all four don't converge together at a single shared vanishing point). You were making this mistake earlier on in your cylinders-in-boxes, but I actually noted that you improved upon it a great deal. As a whole, your box convergences themselves (set aside the additional cylinder corrections) are really showing a lot of strong overall growth since the box challenge. So this one's less pointing out an issue, and more identifying an area of improvement.

So! With that, I'll go ahead and mark this challenge as complete. Keep up the good work.