Starting with your form intersections, the forms and the relationships you've defined between them are coming along quite well. I have just one thing to point out in regards to your use of line weight, in that it seems to be kind of arbitrary, rather than following a particular purpose.

The best use of line weight - at least within the context of this course is to reserve it for clarifying how certain forms overlap others in specific localized areas. By employing this particular tool for a singular, consistent purpose, we're able to communicate more clearly to the viewer. So in this case, employing it right where those overlaps occur to help establish when one form is in front of another, and then blending it back into the existing linework, is what you should be aiming for. Avoid arbitrary reinforcing of the form's silhouette, and avoid applying it to too long a section of line. Here's an example of line weight being used to establish how one leaf layers on top of another.

Jumping over straight into your vehicle constructions, you've no doubt done an excellent job, and your collapsing is well warranted - you deserve a good rest after all the patience and care you've put in. It shows with all of the careful subdivisions, how throughout many of these drawings you've gone the extra mile to ensure that every element you add is positioned and oriented in a specific fashion rather than relying on approximations or eyeballing.

The result across the board is that your drawings feel solid and believable. You've captured the complex, purposefully designed silhouettes of the vehicles quite well, and have done an excellent job of breaking down the specific shape language of each before building it back up. I was especially pleased with the little experiments, like this one, that you used to develop a better understanding of how your forms would be put together, and how they would relate to one another within the context of the main construction.

To be completely honest, the only issue worth mentioning that I noticed was more of a one-off thing. With this tank, you started off with a very isometric bounding box. If anything, it may have actually gotten larger towards the far end, which resulted in a very awkward sense of perspective.

It's obviously a one-off mistake, and frankly the fact that you held to it rather than attempting to correct it is a good thing. It shows that you were adhering to the principles of construction, of working within the decisions/choices/answers given in previous stages, and just pushing forward to keep things consistent (even if consistently incorrect). So, all things considered, you still demonstrated something good here. But since I don't really have any other mistakes to call out, I'm going to take a moment for this anyway.

There's two reasons that this bounding box was incorrect. Firstly, it does look like the intent was to eliminate convergences and stick to not just shallow foreshortening, but an absence of foreshortening instead. I mentioned previously that it was more 'isometric', to use a term you may be familiar with from other areas. It's technically more 'axonometric' though, with that being the broader umbrella term for a projection of 3D space onto a 2D page where all edges that are parallel in 3D space, are also kept parallel in 2D space. Isometric implies specific angle relationships, whereas axonometric is more general.

Now the problem is that axonometric projection is not designed to capture the world as we see it. In this course, we focus specifically on perspective projection, which is designed to maintain a realistic representation of how the world is seen through binocular vision. The reason this drawing ends up looking weird, therefore, is when we interpret it as an attempt at perspective, the lack of convergence tells us that there is no actual distance between one end of that bounding box and the other.

It's the convergence and other representations of foreshortening that convey to the viewer how much of the distance of the given object exists in the "unseen" dimension - that is, the dimension of depth, which cannot be represented as a simple distance on the flat page. The only instance where there is no such 'unseen' element is when the distance itself exists parallel to the picture plane, not slanted towards or away from the viewer. Of course, no element of this bounding box, or the drawing as a whole, is so perfectly snapped to being parallel to the picture plane, and the viewer can of course see that. So, they're left feeling that the drawing is awkward and strange.

There is another reason why opting for even such shallow foreshortening would be incorrect in this instance - a tank is a pretty big object, and the rate of foreshortening we use is determined by two factors: how close the object is to the viewer, and how large it is. Whenever we look at something really closeup - I'm talking right up to the eye - foreshortening goes kind of crazy and gets very dramatic. Move it even a little bit away, however, it reduces quite a bit. Objects that are really, really far away, ultimately get very flat and shallow. On the other hand, when an object is very big, we start leaning back into dramatic foreshortening and sharper convergences.

These factors go hand in hand with matters relating to the orientation of different lines (sharper convergence when the lines are primarily coming towards the viewer, rather than moving across their field of view). With a tank, being of a pretty reasonable size, it won't have crazy foreshortening, but it is going to feature more notable convergences. If it were, however, a toy representation of the tank, then we'd get into much more shallow territory - although never quite eliminating the foreshortening altogether.

As I said - I didn't really have anything else negative to say about your work, but I felt that as I let you go (this being the last lesson of the course), leaving you with an overview of some of the core mechanics of perspective, in such specific terms, would be beneficial. The hope is that you already know much of this, but I find reiterating such things and laying them bare - especially when a student has had loads of experience under their belt so as to better understand it - helps fill in any gaps there may be.

Anyway! You've done extremely well here, and I'm very proud of what you've been able to achieve - both in the quality of your results, and the care, patience, and discipline you've demonstrated in the production of those results. I will happily mark this lesson as complete, and with it the entire course. Congratulations!