Hey there, Penguin! Welcome to Drawabox. I'm sluggy and I'll be going over your submission today, so let's get at it.

Lines

Nice start here. I'm seeing the barest hint of a wobble in your curved super-imposed lines, but I'm not seeing any fraying at the start, so that tells me you're being quite thoughtful with your mark-making. Your ghosted lines look great! Barely any wobble there! Continue to apply the ghosting technique and resist the urge to let your brain get in the way of your muscle memory, so you can iron that wobble out.

From here, I recommend starting to work on your accuracy. You do quite well at hitting the end point consistently, so you can start to focus on hitting it without over- or undershooting. That'll be important for maintaining the illusion of 3D form in later lessons.

Ellipses

Your ellipses are looking very nice. Your marks are smooth and I'm not seeing very much wobble at all, which is great! It looks like you're quite comfortable with this mark. From here, I would recommend tightening these bad boys up by drawing through them a few more times. Likewise, you could train up a bit more accuracy and control with the ghosting technique. You can apply it the same way you do your lines, so you can get those ellipses sitting snugly in their tables, planes, and funnels.

As for your funnels, these are looking decent, but keep a really close eye on that minor axis. You want each ellipses lined up and bisected on that initial line. I do see you playing with the degree of the ellipses as it gets further from the center, which is a great trick for the illusion of 3D. Nice work there.

Rough Perspective

Definitely getting the impression that you're coming in with prior work on 3D. These look great. Your lines are clean and beautiful, and aside from a few stray marks, your horizontals are parallel with the horizon and your verticals are nicely perpendicular. Likewise your depth lines are pretty accurate! You're quickly moving in the right direction, nice work!

Rotated Boxes

Really excellent work on this challenge! Your sense of 3D is clearly on display here and you do a decent job playing with line weight on the front faces of the boxes. Your gaps are consistent and you get very close to that full 180 degree rotation. If you were to attempt this again, then I would also recommend adding in some thoughtful hatching in order to clarify the image. Likewise, to achieve a fuller rotation, you can focus on the VP of each box in relation to the VP of the box before it. Push it far enough along the axis past the previous box and you'll get the boxes to rotate rather than simply move back into space. Overall, however, you did a very nice job with this

Organic Perspective

Lovely work here as well. You do have more than a few convergence errors, but that's nothing the 250 box challenge won't help with. With your line weight, I don't believe you're going back over mistakes, but I would strive to keep it consistent throughout the whole set of lines or establish a clear hierarchy of weights, otherwise, it may cause the image to look incomplete. Overall though, very nice work here!!