Hello G4rinuun, my name is Canoe and I'll be looking at your cylinders. Hopefully you won't be waiting too much longer for your completion badge here.

Starting off with the first 150 cylinders, you're doing a good job of marking where the actual minor axis of your ellipse, even when it's only slightly off. This shows a good attention to detail and will be important for later lessons that deal with man-made objects. There are, however, some instances where your estimated minor axis is incorrect. What I mean by this is that you've marked your ellipses in such a way that your mark splits them into equal areas, but not symmetrical areas. You should be able to fold the ellipse over the minor axis and each half would perfectly cover the other half. Some examples of this issue can be found in the top left and right cylinders on page 19-24, the bottom cylinder on page 73-78, the top left cylinder on page 84-90, and the top center cylinder on page 144-150. You improve your estimated minor axes as you progress through the challenge, but it's still something to keep an eye on. Have a look at how Uncomfy splits his ellipses here if you need a visual for what I'm referring to.

Moving on to some smaller points that don't really matter too much in the grand scheme of things, some of your minor axes show a noticeable arc with results in your cylinders "bending" for lack of a better word (take a look at the topmost cylinder on page 73-78 for an example). You also tend to draw through your ellipses more times than necessary. Try to keep it to 2-3 passes if you can. The bottom left cylinder on page 25-30 and the top left cylinder on page 31-36, among others, show what I find to be strangely dramatic degree shifts (how open or closed the ellipse is depending on how far it is from the viewer) compared to their rate of foreshortening. This is something that I'm sure you'll improve/be able to pick up on as you add this exercise to your warmup pool and explore cylinder in boxes.

Overall, you've done a fine job varrying the rate of degree shifts and the degrees you employ in the first 150. Like the 250 box challenge, having a wide variety of degrees from extremely open to extremely closed will give you more mileage with different types of cylinders. Curiously, you've placed hatching on the far end of your cylinder; that is, the ellipse that is slightly smaller and slightly more open. This was initially confusing to me as the viewer since hatching is normally placed on the closer end of the cylinder like Uncomfy recommends here. However, you've done this so consistently that it might have come down to a misunderstanding on which side to hatch on your part. Either way, do remember that hatching should go on the side that faces the viewer.

Moving on to the fun part of the challenge, I've noticed was that many of your ellipses end up being just ellipses and not circles. What I mean by that is that when a box encloses a perfect circle tilted in space, that box will represent a perfect square tilted in 3d space (this'll come up again in lesson 7, but it's worth mentioning it briefly here). However, a lot of your boxes - at least the ones containing the ellipses - are rectangles instead of squares. This leads to the ellipse not opening its degree up as expected even when dramatically foreshortened. This is most evident in the bottom middle cylinder on page 151-156, all of the cylinder on page 175-180, the top cylinder on page 181-186, the bottom right cylinder on page 199-204, the top cylinder on page 217-222, and all the cylinder on page 246-250. I'd like you to keep in mind moving forward and maye keep as an explanation for why you might feel "wonky" about these particular cylinders, especially as they relate to the minor axis constructed within the box (that you should be checking for during your corrections!).

One things you may have missed on was enclosing your two ellipses into a cylinder. What I mean by this is that you don't seem to be closing the cylinder from the outermost visible edge of the ellipse, rather from a point in the middle. Looking the the example cylinder here, you'll see that the cylinder is enclosed from the outermost visible edges of the two ellipses (and at an admittedly difficult angle to see). You've done this correctly on some cylinders, like the top middle cylinder on page 169-174, but for most others you seem to have gone with the middle approach which lends your cylinder a sense of frailty.

Overall, I think your work here demonstrates a good enough understanding of the concepts of this challenge. However, some of your choices lead to your forms here lacking a feeling of solidity in their execution. So, I'm going to assign you some very minor revisions. These shouldn't take you too long. You're already at 95% and I really think a few extra cylinder can help you clinch that last 5%. Still, you should be proud that you've made it this far. Not everyone does. The cylinder challenge is certainly no joke! Anyway, have fun drawing and I'll see you for your revisions.