Starting with your cylinders around arbitrary minor axes, as a whole your work is looking quite solidly done. You're varying the rates of foreshortening as well as the orientation of your cylinders throughout, and you've been quite fastidious in checking the alignment of your ellipses, catching both more notable discrepancies as well as those that may be missed more easily. This will help ensure that you avoid plateauing in your growth as you continue forward.

My only concern here is a fairly minor one - I'm not seeing the usual tell-tale signs of the use of the ghosting method for your linework here. That in combination with some relatively small issues with some lines wavering, or control not being as good as it could be, suggest that you may not be holding as closely to the specific process of the ghosting method. Keep in mind that this should be employed for all of our freehanded marks throughout this course, so be sure to review the three stages of the ghosting method and how they're employed to refresh your memory on that.

Continuing onto your cylinders in boxes, there's definitely a good bit of improvement over the set. Looking at the earlier boxes, I do get the impression that you may not have been practicing your freely rotated boxes with line extensions (from the box challenge) as part of your warmup - if that's the case, it's important that you continue practicing them. Our warmups are how we can continue to sharpen our skills - the assigned quantity of work that comes with each lesson and challenge's homework assignments are only suited to establish whether or not we're applying those exercises correctly - there's still a need to continue practicing them going forward.

Now, the reason that I say you may not have included them in your warmup routine is simply that earlier on they were pretty rough, with a lot of divergence, but they steadily improved over the set in a way that suggests you were refreshing your memory rather than developing those skills anew.

At its core, 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.

Throughout the second half (200-250) you tend to avoid the more significant divergences, which means we move forward from just worrying about the box construction itself, and into these considerations of proportion. As you continue to practice this in your warmups, keep the following in mind:

• The longer your box gets (in order to accommodate a longer cylinder, so like number 210 on this page), the more likely you are to focus on your sets of edges in pairs - that is, as two groups of two, rather than one group of four, each group belonging to one end of the form. Always remember that they're shared, so when you're executing any one edge, make sure you're thinking about all four of that set, including those that haven't been drawn. The box challenge material was actually updated in the last couple months, and both in that new video material as well as in the Y method video now included in Lesson 1's organic perspective material, there's some useful advice on "negotiating" your box's corners to help keep those convergences as consistent as you can across the full set.

• 250 on this page is a great example of the error checking being applied very successfully - the box itself was drawn without consideration to ensuring the ends would be square, but the line extensions clearly identified this as being incorrect - specifically in having those red minor axis lines go off in a wildly different direction. The fact that you still ensured those minor axis lines were extended in red makes a big impact, because it allows us to clearly associate those lines with the correct set. One issue many students run into is that they'll pick the colour based on the direction of the extension. If they're so far off that they actually start looking like they belong to another set, that can be an easy way to miss critical issues and avoid working on them. The long and the short of it is, while this box was way off, I'm very happy that you stuck to the instructions such that the mistake wasn't easily swept under the rug.

Anyway, all in all, your work is coming along well. I'll go ahead and mark this challenge as complete.