Starting with your form intersections, while the intersections themselves are mostly correct and demonstrate a well developing grasp of the manner in which these forms relate to one another in space, the approach you've used in regards to markmaking, as well as the use of line weight, are kind of off base. I'm going to chalk it up to it having been a long time since your last submission, and no doubt an even longer time since you had a chance to study the principles of markmaking from Lesson 1.

There are a few key issues that stand out here:

  • First and foremost, especially towards the bottom left where you were experimenting with two intersecting cylinders, your linework here is very hesitant - you're holding back in order to make those lines faint and avoid putting too much on the page, and it is having a significant impact on the marks that result. Every mark you draw should have one top priority - to be executed with confidence. Remember that the drawings we do in this course are all exercises - so there's no reason to be going out of your way to hide things, or to use broken/dashed lines.

  • This same issue comes up in your use of line weight. Line weight still follows the same rules of any markmaking, requiring a confident execution. It's very easy to get caught up in tracing hesitantly back over your existing linework, but this focuses too much on how those lines sit on the flat page, rather than how they represent edges flowing through the three dimensional world. It also causes the linework to stiffen.

  • Also in regards to your line weight, it should always be kept very subtle, like a whisper to your subconscious. Better still to reserve it just for the localized areas where overlaps occur, as shown in this example of two overlapping leaves.

Moving onto your cylinders in boxes, these are coming along decently, though I did notice some of these boxes had some sets of lines that were running parallel on the page (in 2D space). Remember that this (that is, a vanishing point going to infinity as discussed back in Lesson 1) only occurs when that set of lines is actually running perpendicular to the viewer's angle of sight, straight across their field of view and not slanting towards or away from them at all. Otherwise there must be at least some convergence, even if only very gradual.

Finally, onto your vehicle constructions. Now your work here is very, very, very well done. As far as all the principles of the lesson go, you've done a great job - shown considerable patience and care in subdividing your volumes to find precise positioning for your constructional elements, and using the various techniques covered in the lesson to great effect. I can also see your confidence with this stuff improving considerably throughout the set, with your later constructions demonstrating a lot more boldness without sacrificing those constructional steps.

There's just one issue - which in the grand scheme of things is not such a big deal, but it is still worth calling out. The issue is that in the section discussing the tools for this lesson, it's specifically stated (in the area highlighted here), that you should not be switching pens in the process, and should be using the same pen for all your linework, including the construction and subdivision.

This basically goes back to the same issue as discussed in your form intersections - you approached the drawing itself as being something separate from the underlying construction. The drawings we do throughout the entirety of this course, are themselves, the exercise. They're three dimensional spatial puzzles that we work through to help rewire the way in which our brains perceive three dimensional space. There is no point at which we put that stuff down, and then trace back over our work to create a separate, "final" drawing - not for the work we do here.

Aside from that, you've done a fantastic job. Just remember - this course is all about the exercises. It's not an opportunity to perform (where the end result itself matters). Rather, we make sure to put all our energy towards thinking in 3D space, into establishing how the forms relate to one another in space, and so on. The moment we switch over to that different pen, to getting into the clean-up pass, we start thinking about tracing back over lines in 2D, which definitely can muddy the intent of the exercise itself. It's totally fine for one's own drawings outside of the course, and it certainly can work very well as a process for achieving finished work, but in the future, when you go through drawings like this to help further train your spatial reasoning skills, leave the finished drawing out and focus wholly on construction from start to finish. That'll help keep things focused.

So! All in all, it is very clear that your spatial reasoning skills have developed phenomenally, and based on the underlying construction that you demonstrated in pages like this one and this one and this one, you certainly do understand the principles of this lesson. I will happily go ahead and mark this lesson, and the entire course, as complete. Congratulations.