Starting with your cylinders around arbitrary minor axes, I noticed pretty quickly that you didn't include much variation in the rates of foreshortening for this set, though it was requested (in bold) in the assignment section. That said, I'm less concerned about that, and more concerned about instances where you actually drew cylinders with no foreshortening at all. Fortunately this wasn't all of them, though it was especially prevalent towards the beginning, then came up here and there throughout the remainder.

Drawing these cylinders with side edges that are parallel on the page - meaning, converging towards an infinite vanishing point in the manner discussed in Lesson 1 - is actually incorrect. We do not directly control where our vanishing points are - rather, we control the orientation we want for a given set of edges in 3D space. It's that orientation that then determines where the vanishing point that governs those edges will be situated. Vanishing points at infinity occur in a limited set of circumstances - namely when the set of edges in question run perpendicularly to the viewers' angle of sight, effectively not slanting towards or away from them through the depth of the scene, just running across their field of view.

Given that the cylinders we draw in this challenge are randomly rotated, the chances of achieving that perfect of an alignment once in a set of 150 is slim enough that it's best left out, instead including some convergence, even if only slightly (like the other cylinders in your set).

While this issue is unfortunate, the rest of this section of the challenge looks fine. You've got good control of your ellipses, and are drawing them confidently, and while your alignment checks show very small deviations in most cases, it's simply because you are quite good at aligning them, and not that your minor axis lines are especially far off from correctly identifying your minor axes.

Continuing onto the cylinders in boxes, you asked for more solid strategies for drawing squares at different angles - and unfortunately, this is it. At least, as far as this course is concerned. To be more specific, that's the goal of this exercise. It's 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 you have applied the exercise correctly in most cases, but not everywhere. There are cases where you deviated from the instructions by drawing ellipses that would only touch some edges of the plane enclosing them - for example, 230, 229, 234, 244, etc. As a result of this deviation, the line extensions you were checking for each of these ellipses were not relevant to the plane's proportions, and thus didn't really give you any information on how to alter your approach.

Fortunately while this issue wasn't rare in your set, it wasn't the majority. Just be sure to draw an ellipse that touches all four edges when practicing this exercise in the future.

All in all - not the best you could have done here, but going forward you should be able to make better use of these exercises. I will still be marking this challenge as complete.