Starting with your form intersections, your work here is by and large coming along well. I am noticing some wobbling in your linework, which suggests that you may want to ensure that you are using the ghosting method in its entirety (including the confident execution at the end). Some students will slip back into the tendency to put less time into the planning/preparation phases, and compensate with executing more slowly and carefully, which will cause your lines to wobble. The intersection lines thesmelves however demonstrate a good grasp of how these forms relate to one another in space.

Your cylinders in boxes are coming along as well, and you're applying the line extensions correctly to test your proportions, so you're on the right track to continue employing this exercise to further develop your instinctual grasp of how to create squared proportions for any plane in 3D space.

Continuing onto your form intersection vehicles, these are done really well. These confuse students sometimes, and they'll push these far further than intended, but you've applied the exercises exactly as you should, as a simple extension of the form intersections exercise, with the forms arranged in the general layout of a vehicle. This does a great job of establishing the simple fact that vehicles, complicated as they may be, are still made up of basic forms arranged in a particular fashion. This reflects nicely in how you tackle the more detailed vehicles as well. You're not just laying out a bounding box and then drawing the vehicles from observation within it - you're using the bounding box to enclose a space, and then focusing on the forms that need to be built up within it, using that structure to help define where they should go, how big they should be, and how they relate to one another. This of course comes heavily from the fact that you're employing those proportional studies exactly as you should be - by your own description, using them as a tool to do all your observation (or as I'd phrase it, making all your decisions), so that building up the vehicle in 3D is merely a matter of following a formula you've already established. Very nicely done.

There are a few points I want to call out - none of which are critical - although some do suggest that you may have missed some instructions, both in the lesson material and even from the wheel challenge critique, although I expect the latter is because of how much time has passed since you received that critique. Still, it is your responsibility to ensure you're reviewing that feedback as needed to ensure you apply it going forward.

To start with that point, as we can see in the tires on this tractor, you filled in the side planes of the individual tread chunks (the protrusions from the surface of the tire) - which is essentially form shading, which as discussed here in Lesson 2 is something we generally avoid applying to our constructions in this course. I also explained this further in the wheel challenge critique, as mentioned above.

This comes up in small ways elsewhere in your constructions as well, in terms of filling in areas of black that aren't necessarily intended to represent cast shadows. The only exception to this which is totally fine is filling in the interior shapes of your cars (as we see here), where we can kind of argue that the cab structure is casting shadows inside, which are falling upon the surfaces within. It's not entirely accurate, but it's good enough and it helps avoid having the interior structure make the construction more confusing. Much of what we see here however - the solid black in the grill, the filled wheel wells, and the strip along the door - all fall into either form shading, or capturing the local colour of the surface material, which should also generally be ignored.

Another point to keep in mind is that as explained here (specifically where the instructions allow you to use ballpoint), it does say that you should not then switch pens to fineliner to do any sort of a clean-up pass. So basically, if you use ballpoint, stick to ballpoint. While this wasn't as pronounced as the other issue, I can definitely see cases where you switched up the type of pen you were using, as we see here. This isn't a huge deal, but it does lean more towards treating later passes as a clean-up pass, which would require you to trace over existing linework (which itself can cause us to focus more on how those lines rest on the page in two dimensions, rather than how they flow through three dimensions of space).

All that said, you've still done a great job with this lesson, and I'm definitely seeing the considerable patience and care you've taken with your work on display throughout. I especially felt this truck was really strongly constructed, even if the wheels got wonky (no doubt due to the fact that ellipse guides are a pain to get to cover all your sizes).

So! I'll go ahead and mark this lesson, and the course as a whole, as complete. Congratulations! And just in time to flex more of that 50% rule confidence with the upcoming promptathon.