Starting out with the first set - the 150 cylinders around arbitrary minor axes - I can definitely see a fair bit of improvement specifically in aligning your ellipses more consistently to that central minor axis line. As you progressed through the set, you steadily got closer more frequently. It's not that you didn't have some significant deviations (like 146's top face) but the margins of error and their frequency definitely shrank overall, showing definite improvement.

I did however notice that you didn't really adhere to what was requested in the homework assignment section in bold (as shown here). The rate of foreshortening remains roughly the same across most of your cylinders. For those limited rates of foreshortening, everything seems to be roughly in order, but it's hard to tell how you'd approach drawing your cylinders for more dramatic cases. What I'm really looking out for is whether the shift in scale from one ellipse to the other remains consistent with the shift in degree.

A common mistake students make is to draw the far end much smaller, but still maintain the same relatively limited shift in degree. Both of these 'shifts' serve as visual cues of the cylinder's length (more dramatic shifts imply a longer distance between the ends), and so if they are inconsistent, it would suggest an incongruity, with one element suggesting a longer cylinder and the other suggesting a shorter one. So, even though we weren't really able to test that in your work here, do keep that in mind.

Moving onto your cylinders in boxes, your work here is (amidst all of the clutter) really well done. You've approached the exercise with a lot of care and conscientiousness, and you have definitely developed your ability to estimate the proportions of your boxes quite well. That is ultimately the focus of this exercise - to train students to more consistently bang out boxes that feature two opposite faces with are square in proportion. It's the sort of thing that helps a lot with what we draw in lesson 6.

We achieve this by adding the additional line extensions. Where the box's own lines point towards its own vanishing points, when the ellipse's various lines also converge towards the box's vanishing points, it suggests that the ellipses contained within the box's planes represent circles enclosed within squares. As we test those alignments and adjust them time after time, we steadily bring them closer and improve our intuition for how those boxes should be constructed in the first place.

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