Jumping right in with your form intersections, overall you're doing quite well. This exercise is one that really captures the essence of the course, and as such it's one we introduce early and circle back to at a couple points across the lessons. This allows us to gauge how the student's spatial reasoning skills are developing. At this point it's normal for students to be fairly comfortable with intersections between different flat surfaces, but to still struggle with those involving curved ones, especially those intersections with two curved surfaces. In your case, I'd say you're a little further along than that, in that your curved-on-flat intersections are solid, but you do still have some issues handling those with multiple curving surfaces, as I've noted here. This is still entirely normal, and as I said you're further along than most at this stage.

The main thing to keep an eye on is identifying the ways in which the surfaces in question curve, and using that information to piece together the resulting complex intersection line. This diagram shows how we decide which directions of curvature we focus on, as well as how the intersection line changes if we replace a hard edge between two flat surfaces with a more gradual, rounded transition. Hopefully they should help, but of course it'll be that information in combination with further practice of the exercise that'll be necessary to really solidify it.

Continuing onto your object constructions, you've done a fantastic job. You've been extremely fastidious with the use of your orthographic plans and have pushed those subdivisions as far as they could go prior to graduating over to the 3D construction. The benefit to that is that you don't actually have to do that much additional thinking in order to build it up in 3D space. Or more specifically, your mental resources end up focused purely on how one would transfer the steps taken in 2D, into 3D, rather than having to make all the decisions at the same time.

In doing this, you've adhered very well to the principles of precision that are held up throughout this lesson's concepts and instructions. 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 truth, I have just one very mistake to call out, and rather than being related to the concepts we're studying in this course, it's just an instruction that you missed that I want to ensure you don't miss in the future. In the section that goes over which tools we're allowed to use, I mention that we can use ballpoint pen (and that if we can, it's better to do so), but that we should not be changing pens in the process. In other words, if we use ballpoint, we want to stick to ballpoint. Reason being, we don't want students to trace back over their existing linework to create a separate "clean-up pass", as the mindset this tracing demands is one that focuses on how those lines sit on the flat page, rather than how they represent edges in 3D. Ultimately your work didn't suffer much for this, but it's still best to build up the whole construction with ballpoint, and to avoid tracing back over lines. Another way of thinking about this is that the scaffolding/construction is part of the final result, and so there's no need to separate them. It's all just a puzzle forcing us to think through the relationships between different elements in 3D space.

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