Starting with your cylinders around arbitrary minor axes, you definitely do have something of a rough start here, although you appear to correct that somewhere after the first hundred. The nature of this major issue however is admittedly rather disconcerting - it's that for the first hundred or so, you were pretty consistently drawing the ellipse on the farther end of each cylinder with a narrower degree than the end closer to the viewer, when it should always be wider than the end closer to the viewer.

This is something we introduced way back in Lesson 1's ellipses section, with the video there demonstrating the concept using physical props, alongside this explanation here. Furthermore, in the challenge notes itself repeats this concept here. While you did ultimately correct this, you may want to reflect upon why exactly this occurred, given that it is a concept that comes up frequently throughout the course (in the context of contour lines as well). It may suggest that you are not appropriately applying exercises from previous lessons as warmups as explained here in Lesson 0, that you may need to revisit the instructions and notes for past content more frequently in order to keep from forgetting, or that you may not be reading through the instructions of the task at hand as carefully as you should be.

There are a couple other things I wanted to mention:

• Your linework is generally looking pretty good and confidently executed, although there are a few very small cases of hesitation/wavering - really very minor ones. I wouldn't worry about this in most cases, but I did notice that while you do have the start/end points we apply in the planning phase of the ghosting method present for some lines, it appears to be applied inconsistently. This suggests that there may be room to apply the ghosting method more fully, and more consistently in all your lines, and this may help iron out that last little bit of hesitation.

• Once you resolved your degree shift issue, after the first hundred, you appear to have largely applied it very well throughout the rest. This includes something I didn't actually explain in the material, as I prefer to give students the chance to figure this out on their own throughout the challenge (and I explain it at the end in the case that they didn't catch it themselves, or if they did but it's unclear whether that was subconsciously, or whether they're entirely aware of the why behind it). This comes down to the relationship between the degree shift (closer end is narrower, farther end is wider), and the shift in scale from one end to the next - both of which serve to convey how much foreshortening is being applied to the form. It's that foreshortening which tells the viewer how much of this form's length can be seen directly there on the page, where we can measure it with our eyes, and how much exists in the "unseen" dimension of depth. Because they represent the same thing, the shift in degree and the shift in scale must operate in tandem - so we want to avoid cases where we have a very dramatic shift in scale with rapid convergence of the side edges that is matched up with a much more subtle shift in degree. This can make a cylinder feel off to the viewer, even if they're not sure why. Of course, as I stated, this is something you appear to understand, at least on a subconscious level.

Continuing onto your cylinders in boxes, here you've generally done fairly well, although I do have some cases to point out where I want to make sure you're interpreting the results correctly. 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.

Now, overall you've applied this pretty well, and I'm definitely seeing improvement over the set. There are however some outliers that I just want to make sure you're interpreting as intended. The main one that jumped out at me was 249, where the minor axis of the farther ellipse is way off its alignment, as is the green contact point line of the closer ellipse. What this tells us is that the proportions of the box itself are way off, resulting in an ellipse that is very far off from representing a circle in 3D space aligned to the face of the box.

As long as you do understand what those lines being off means, then you'll have the kind of information you'll need to continue building upon it and improving. Though I will note that you should be sure to extend all of your lines fully. In that same example we can see that your minor axis lines are much shorter, making it harder to compare them with the other lines they're meant to converge with. This can make it harder to gauge when the discrepancies are less severe.

Anyway, I will be marking this challenge as complete. Just be sure to keep everything I've said here in mind.