Jumping right in, I'll admit that this critique is (hopefully) going to be a short one, for one simple reason: you've knocked it out of the park. Just at a glance I can see one critically important thing: you have very clearly held up your end of the bargain, which is to invest as much time as you require to execute the work to the best of your current ability. I can see it in your linework, where you apply the principles of markmaking and the phases of the ghosting method to great effect, and I can see it in how you've tackled each object construction in a step by step manner, focusing only on what you were doing in the moment rather than trying to take on multiple problems at once (something that often results in solving each more poorly than if we'd have simply focused on one at a time).

Starting with your form intersections, you're demonstrating a very well developing understanding of the relationships between these forms as they exist in 3D space. I have just one relatively minor complaint - when drawing your intersection lines for this exercise, don't draw them in a different colour. I know that the diagrams that come with the exercise instructions do highlight each new intersection line in red - that is merely to highlight what's new, so it is clearer to the student. When it comes to actually doing the work, drawing the intersection lines in a different colour can convince our brains that these intersection lines are somehow separate from the forms being drawn, that they're an additional analysis (like the line extensions), but not part of the scene itself. It actually helps immensely to recognize that they are actually physically present - that like the seams we get when welding two pieces of metal together, they introduce new edges between them. Drawing them with the same colour as the forms themselves helps reinforce this idea.

Of course, I'm not at all concerned that you're somehow not understanding how the intersections exist relative to the forms that are drawn - in this, your work speaks for itself. Just that these are the best practices to follow for this exercise going forward in your own practice, and if you in the future provide another student advice on how to employ them.

Continuing onto your object constructions, what really takes the cake here is the sheer depth of subdivision you were willing to break each object down to, and the excellent use of orthographic plans that you leveraged in order to see it through. These constructions cannot have been quick things - they will have required great patience, and greater time. It is not uncommon for students to struggle with this (and it's probably one of the bigger things we address in this lesson, as we lead into Lesson 7 where the demands on students and their time only increases), but you've demonstrated very clearly that you are willing to put in what it takes.

The only real thing I can think to mention in terms of something that could have been done better is in your speaker construction. This one features a lot of organic curves to it, and while you frankly did a great job at pinning them down in a manner that came out feeling solid, this is an area where many constructions can very easily suffer. Such curves simply don't easily hold that illusion of solidity on their own, so starting out with them can be a liability for these kinds of exercises. Instead, as explained in this section, constructing them first as a chain of straight edges, or flat surfaces, as though we were carving the object out of wood, yields solid results more consistently. This is something that will be considerably more relevant in Lesson 7. Cars have a lot of curves to them, but it's generally best to start them out as boxy as possible, and gradually carve them down.

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