While it is indeed something students are better off not doing, the way in which you've done it here is actually not that big of a deal. In most cases (except for when you're dealing with sphere-cylinder intersections for some reason) you're still only drawing the visible portion of the intersections, except when you're drawing an entire intersection that would be obscured from view. This means you're not falling into a lot of situations where this choice actively makes the exercise harder to critique by making the intersections harder to visually parse.

So - stick to the visible ones only in the future, but it's not a huge deal. And by and large your work here with this exercise demonstrates a fairly well developing understanding of the relationships between these forms in 3D space. Where we generally only expect students to be comfortable with intersections involving flat surfaces at this stage, and to still have some uncertainty when curved surfaces are added to the mix, you seem to be reasonably comfortable with the curving surfaces as well. The only issue that jumped out at me was this one, which based on how it handled the the left/right sides of the intersection in different ways, suggests that you were really unsure in that moment and just kinda winged it. Thinking about the individual surfaces, and about which cross-sections of the forms are relevant to your intersection, can help with solving these trickier problems. This diagram also demonstrates a similar concept.

Continuing onto your object constructions, your work throughout this lesson is similarly well done. You've taken a the core principles espoused throughout the lesson to heart, and that shows in just how much effort you've put in to increase the overall precision of your approach, and the control over the result. That is exactly what this lesson is about.

Precision is often conflated with accuracy, but they're actually two different things (at least insofar as I use the terms here). Where accuracy speaks to how close you were to executing the mark you intended to, precision actually has nothing to do with putting the mark down on the page. It's about the steps you take beforehand to declare those intentions.

So for example, if we look at the ghosting method, when going through the planning phase of a straight line, we can place a start/end point down. This increases the precision of our drawing, by declaring what we intend to do. From there the mark may miss those points, or it may nail them, it may overshoot, or whatever else - but prior to any of that, we have declared our intent, explaining our thought process, and in so doing, ensuring that we ourselves are acting on that clearly defined intent, rather than just putting marks down and then figuring things out as we go.

In our constructions here, we build up precision primarily through the use of the subdivisions. These allow us to meaningfully study the proportions of our intended object in two dimensions with an orthographic study, then apply those same proportions to the object in three dimensions.

You've been incredibly fastidious and patient in your use of orthographic plans. The robocup was especially complex, but you broke it down extremely well, and that shows in how succinct and economical your reconstruction of it in 3D space ultimately came out. That is to say - not a single subdivision or stroke was wasted, everything served a purpose and contributed to the result.

Admittedly you may have noticed that the proportions on your stapler construction were off - but this is not in the scope of this lesson a mistake, as we simply haven't yet given you the tools to transfer measurements across from one dimension (say, the side view) to another (the front or the top) - in effect, we haven't yet gotten into what it takes to construct a cube. This will be addressed in Lesson 7, so you needn't worry about that - I just wanted to make sure that you understand this was not the result of a shortcoming or misunderstanding on your part.

I genuinely have no complaints. You've implemented every aspect of the lesson, and you've done so in a manner that professes a solid grasp of each concept. So! Without further ado, I'll go ahead and mark this lesson as complete. Keep up the great work.