Starting with your cylinders around arbitrary minor axes, your work is largely well done, although I am seeing a number of cases where your side edges were kept fairly parallel on the page, as though their vanishing point were at infinity. We can see this in cases like 70, 85, 92, 118, among others - so it's definitely present throughout the set. As such, I wanted to point you to this explanation as to why this would be incorrect, given the fact that we're rotating these cylinders randomly throughout the set.

This is a kind of issue that has resulted in significant revisions for some students, but as this is an issue that only came up sporadically throughout the set, and that the rest of your work is honestly very well done throughout this section, especially with the fastidious checking of your minor axis alignments and all, I will instead leave you to address that in your own practice.

Carrying onto your cylinders in boxes, your work here is very well done. 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 being as conscientious as you been with your line extensions, being sure to extend each and every one as much as possible (including the minor axis lines, which some students end up identifying in the manner used for the previous section, which can make it a little less easy to identify discrepancies in how they converge towards the box's VP), you've armed yourself with all the information you required to continually assess your approach and adjust it accordingly. I can see your estimation of your boxes' proportions improving across the set, which in turn brings those convergences together more consistently, so all in all you're very much on your way here.

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