Hello Rodri_113, congratulations on making it through all 250 cylinders. I’m here to give you some feedback.

Starting with your cylinders around arbitrary minor axes, good work. Your ellipses get smoother and more confident across the set, and you’re pretty conscientious abut drawing through them all. Your straight lines mostly look pretty good too, and you’re doing a great job of checking your ellipses' minor axes, though I spotted a couple you missed, like 140, 109 the far side of 126, 7.

On the whole you’ve done great at making the ellipse at the far end of your cylinders have a slightly wider degree than the ellipse at the near end, which is correct. However you have drawn a significant number of cylinders where your side edges remain extremely parallel on the page (which is incorrect, given that this only occurs when that set of edges runs perpendicular to the viewer's angle of sight, not slanting towards or away from them through the depth of the scene, and this challenge has us rotating cylinders randomly so that perfect of an alignment is unlikely to occur)

When we analyse the two ellipses for a cylinder there will be two differences between them. These differences include the shift in scale, where due to the convergence of the side edges the far end becomes smaller overall, and the shift in degree where the far end gets wider than the end closer to the viewer. The thing is, we need to make sure that both of these "shifts" occur in tandem. Should one shift be dramatic and the other shallow, it creates a contradiction that the viewer will pick up on, noticing that something's "off" even if they don't specifically know why.The reason for this is that both of these shifts are manifestations of foreshortening, and they convey to the viewer just how much of that cylinder's length is visible on the page, and how much exists in the unseen dimension of depth, which cannot be conveyed as distances on the flat piece of paper.

So for example looking at 81 and 82. 81 has a shift in degree, but not in scale, and it looks a bit off. But on 82 the ellipse has a shift in degree and a shift in scale, and I think it looks more believably 3D.

It would have been beneficial to include more variety in your cylinders, through different sizes, proportions, viewing angle and rate of foreshortening. There are lots of options you can play around with. And I would encourage you to continue to do so during your warm ups.

Moving on to your cylinders in boxes, you’ve done a very good job! Your markmaking continues to be good and you’ve applied your line extensions correctly. 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. Your perspective estimations show a great deal of improvement across the set, as you develop your subconscious understanding of space through repetition, and through analysis (by way of the line extensions). Great work.

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