Starting out with your form intersections, these are generally well done and show a well developing grasp of how these forms relate to one another in 3D space, although the box intersection in the middle of the second page was notably off so I put together a quick example of how those two boxes would intersect more realistically. I think the right side ended up getting a little confused, which certainly can happen with all the lines flying around on the page. One other thing to keep in mind is just how you're going about applying line weight. Right now there's a visible jump when the stroke you added to build up weight ends, back down to the original weight of the initial line. What we want to be doing is adding this line weight with a confident stroke driven by the ghosting method, so our marks have a natural taper to them, allowing them to blend back into the original stroke. This taper occurs when drawing without hesitation, because the pen would still be moving while being lifted off the page.

Moving onto the actual constructions, it's fair to say that you did not take this lesson lightly. Students at this stage are just getting used to starting to subdivide things more than they usually would, and often still end up estimating or eyeballing things beyond a certain point. Of course, to eyeball anything in this exercise is a mistake, but it is one of those "accepted" things as students get used to just how far they can push this kind of approach.

Needless to say, the amount of patience and care you've invested in each and every one of these drawings is incredible, and in each one it has paid off immensely. As far as technique goes, you're doing an excellent job across the board. There is only really one thing of note that I want to touch upon, and I'm honestly not super concerned about it: some of y our lines tend to get pretty hairy.

It's generally anything that curves - you go back over them a great deal, likely to build up line weight, but I suspect that it may in some small part also be to help refine the marks you've put down, in cases where maybe you haven't been entirely satisfied with them. I can't stress this enough - you need to get into the habit of making a single mark for a single line. Even if it doesn't come out the way you intended it to, leave it as it is. Mistakes happen, that's the natural way of things, but the more we allow ourselves to just go with the marks we've made, the more we improve our ability to actually pivot with those marks and continue to make the drawing feel polished without going back over them all.

Now, it's obvious that a major factor in how these drawings are made is the fact that you're forced to deal with all of these construction lines, and you need some way to bring your drawing out from the forest, and line weight is obviously the tool for that job. That shouldn't have to mean having a dozen different strokes present following the same path, though. Keep your line weight to limited sections of line, rather than stretching over too great a distance, and if you're freehanding them, make sure you apply the ghosting method and draw from your shoulder. You will probably slip up here and there slightly, but you don't need to keep going back over it. Taking a step back, you'll notice that these small gaps in your lines aren't really that big of a deal - they only become a problem when they start forming a forest of their own.

Line weight is at the core of it really just about clarifying specific overlaps between forms. It's not about reinforcing the entire silhouette of an object, even though that may be what you think you need to do in order to bring it out of all those construction lines. Being a little more subtle can still have the same kind of effect of the image emerging from the mess, so I recommend strongly that you take a step back and try to have a lighter touch. Fewer marks, but ensure that each mark bears as much preparation and planning as it requires.

Of course, with this lesson and all those ahead you have every freedom to use tools like ellipse guides, rulers, french curves to make the linework clean and precise, and as you move beyond this lesson I strongly encourage the use of rulers/ellipse guides at the very least. Ellipse guide sets can be expensive, but most students opt to grab a "master template" (like this one listed here in the recommendation page). They're more limited in terms of ellipse size, but are entirely workable for most of the needs of the 25 wheel challenge and lesson 7.

So! Anyway, with that I'll go ahead and mark this lesson as complete. Keep up the fantastic work.