While overall your work is well done, there are a few points that give me somewhat mixed feelings about how this was approached. Starting with your cylinders around arbitrary minor axes, you generally stuck to keeping your cylinders to a fairly shallow foreshortening - basically avoiding cases of particularly rapid convergence for the side edges. This was a bit of a red flag at first, specifically relating to what's explained in this section of reminders - talking about how forcing a vanishing point to infinity for arbitrarily rotated forms being incorrect. Looking more closely at your work however, you appear to only do that particular thing very rarely - we see it in number 60 on this page, on 68, 69, and 72 here, 119 here, 147 here, etc.

Overall the issue is certainly present throughout your work (and there are certainly others I didn't call out), but looking at the set as a whole I believe the issue is that your intention was to always work with shallower foreshortening, and sometimes you just got too shallow unintentionally. The intent is important here - but that doesn't mean you haven't made a mistake. The same section of reminders I linked above talks about the issue that is present here as well: the homework assignment asks students to vary their rate of foreshortening throughout the set, from shallow to dramatic, and that is something you neglected to do.

Aside from that however, your work is generally very solid. You're checking the alignment of your minor axes quite fastidiously, your ellipses are evenly shaped and your lines are executed with a great deal of confidence. Just be sure to follow the instructions more carefully in the future.

Moving onto your cylinders in boxes, your work here is generally pretty solid. Towards the beginning (mainly on that first page) you were definitely prone to forcing vanishing points to infinity (we can see this in cases like 1 and 2) - this again is incorrect, and while the reminders linked above explain why, it's also explained here specifically in regards to boxes. Fortunately this issue appears to disappear rather quickly, and you're much more actively ensuring convergences throughout the rest of the set.

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.

In applying the line extensions correctly and consistently (for the most part) throughout the set, you've armed yourself with the information you require to continue honing those instincts and expanding what your brain can do without conscious intervention. There is however one minor issue (hence the "for the most part") - when you extend the minor axis line, do so for each ellipse, separately. Right now you appear to be extending a single line through both ellipses, which assumes that both ellipses are aligned to one another, which they may not be. So, in essentially extending an average of the two, you're giving yourself a little less valuable information to work from.

Anyway, I'll go ahead and mark this challenge as complete.