Starting with your form intersections, overall you're doing a pretty solid job here, although there were a couple little issues I noticed that I wanted to call out. I've marked them out here. For the cylinder/box intersection, remember that the end of the cylinder is flat - so where it intersects with the top plane of the box, you're looking at an intersection between two flat surfaces, which would be represented with a straight line. For the sphere-box intersection below, you were on the right track but had your intersection lines inverted, such that they did not follow the surface of the sphere itself.

Always remember that intersections occur between different pairs of surfaces, and so we always want to ensure we're considering how those individual surfaces move through space. This diagram may help with this - it demonstrates how we think about the individual surfaces, how the individual intersection segments meet with sharp corners at the edges where we shift from one surface to another, and how that sharp corner changes if we are to replace the hard edge with a softer, more rounded transition.

Continuing onto your object constructions, I think you've done a fantastic job, not only in producing constructions that feel solid and are visually pleasing, but especially when it comes to holding to the core principles of the lesson, and applying the instructions very specifically to each task. In particular, this lesson focuses heavily on the concept of precision, shifting from the more reactive inside-out approach we used in previous lessons (where we could account for mistakes from previous stages by simply adjusting how we'd add subsequent forms onto the structure in order to achieve a result that is still solid and three dimensional, even if it doesn't match the proportions of the reference perfectly), to one that focuses more heavily on more specific planning.

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.

This in particular is something you applied extremely well - your use of proportional studies is excellent, and you've taken great care to figure out the entirety of your construction in plan form, before then applying the same principles to your 3D construction.

I really don't have too much in the way of actual critique here - really, just a couple very minor things:

• For this padlock, leveraging the use of straight edges to define your curves first (especially for the curves along the upper section of the locking bar) would have helped give you more landmarks against which to build those curves. In other words, you jumped into the curve a little too soon, so review these notes and take another look at the coffee mug demo linked there. This would also be useful for the back edge of your blood pressure machine.

• For your blemish stick, I noticed specifically on the 3D construction side, the lines in your subdivisions are pretty wonky when it comes to their convergences towards their intended vanishing points. Something to keep in mind in regards to this is that since we're allowed to use rulers (and mind you that's not a kindness, it's encouraged as explained here), those rulers aren't just useful in executing consistently straight lines. They also allow us to see a visual extension of the path that line is going to follow, allowing us to gauge the convergence that orientation will result in, without having to commit to drawing it first. It's just a matter of taking the time to consider this "free" extension, so we can take more care in laying out those lines.

• Another point about the blemish stick - from the top view, you drew the circle shifted to one side, rather than touching all four edges of the enclosing plane. If this was intentional (and it appears to be since you did the same in the 3D construction), remember that construction is all about maintaining very tight, specific relationships between our structures. You never want an arbitrary, "floating" relationship between elements - so in this case, you'd lay down more structure/scaffolding to ensure that circular top is tightly enclosed. In this case you're relying on estimation and observation to judge the correct distance from the right edge. Fortunately most of your other constructions tend to avoid these kinds of "skipped" steps, but I definitely wanted to call it out here so we can avoid it in the future.

Anyway, all in all, great work. I'll go ahead and mark this lesson as complete.