Starting with your cylinders around arbitrary minor axes, these are fairly well done. You're drawing the linework (both the straight lines and ellipses) with confidence, and you're playing with a wide variety of rotations. You're also fastidious in checking your ellipses' true minor axes, although I certainly would have preferred this to be done in a different colour so it would be easier to differentiate.

One thing I did catch was that you didn't really vary the rate of foreshortening for your cylinders, more or less sticking to the same middling rate - not super shallow, not super dramatic. While there are worse mistakes one can make (I have students who draw with absolutely no foreshortening whatsoever sometimes), and I can see that you've understood how the two manifestations of foreshortening - the shift in scale and the shift in degree from one ellipse to the other - need to work in tandem with one another to maintain a consistent illusion of foreshortening. I'm not seeing any cases where you've got a lot of scale shift (where the far end gets much smaller) and minimal degree shift (where the far end remains roughly the same width as the closer end), or vice versa - so that's certainly good. Just remember that the request for variation in foreshortening was listed in the instructions in bold.

Continuing onto your cylinders in boxes, these are coming along nicely, though I do have one suggestion to help you get more out of them. Right now you're doing a good job of extending your boxes' edges, as well as the minor axis line - but the contact point lines for each ellipse (in blue) aren't extended nearly as much.

This exercise basically trains students' instincts in regards to constructing boxes that feature a pair of opposite faces which are proportionally square. We do this by using the ellipses more as a tool for analysis - similarly to the line extensions. By checking how far off we are from those three lines for each ellipse (the contact point lines and the minor axes) are from converging towards the box's own vanishing point, we can find out how far off we are from having those ellipses represent circles in 3D space, and in turn, how far off the planes that enclose them are from representing squares in 3D space.

Right now you're extending each of these contact point lines a little in both directions - instead, extend them back in space, away from the viewer only, and do so as far as you would all the other lines.

Aside from this, you're handling this exercise well too (except for 179 where you extended one of your box's set of lines towards the viewer instead of away), and I can see that your estimation on those proportions is improving - though it would definitely improve more efficiently when extending those lines further than you have been.

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