Starting with your form intersections, overall I'm pretty pleased with the progress you're showing. At this stage I expect students to be fairly comfortable with intersections between different flat surfaces (which by and large you are), while still showing some issues with intersections involving curved surfaces. In your work, you're actually handling a lot of such curved intersections reasonably well, although I did notice a variety of issues which I marked out here. The main ones of note would be:

• In the top-right where you've got the sphere intersecting with the box the main issue is that the intersection line appears to follow a single trajectory, but should actually be two distinct intersection lines that meet together with a sharp corner at the box's edge. Reason being, it's an intersection between the sphere and the plane to the left, and an intersection between the sphere and the plane to the right. Two separate intersections. Additionally, your intersection line's curvature needs to be shallower - I believe we'd only get an intersection as curved as you drew it if the sphere were actually in front of the box, and it was the very pole of the backside of the sphere which was intersecting with the box.

• For the cone-cylinder intersection near the middle-top of the page, I corrected the intersection as being composed of two separate straight lines, instead of one straight and one curved. Reason being, the surface along the cylinder's length is actually straight in one direction, and curved in the other. In this case, your cone is pretty close to being aligned to the lengthwise direction of the cylinder, which would result in the line being straight. In all fairness, the alignment isn't so perfect, but it's not off enough to give us much of a visible curve.

Carrying onto your object constructions, overall you've done a pretty fantastic job. What I'm paying attention to most here is the heavy emphasis on precision in your approach, which is really at the core of this lesson and is really what differs most between this lesson (and lesson 7), and lessons 3-5. Where the previous lessons was built up inside-out, where we could deal with any proportional misjudgments by simply adjusting the size of the forms that were added thereafter to compensate (allowing us to still achieve our priority of structural solidity and the illusion of three dimensional forms, even if the proportions are off), these last couple of lessons require us to work outside-in. As a process this requires us to be much more careful with how we plan things out.

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 your constructions here, you've built up a great deal of precision through the heavy 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, breaking the whole process down into stages and steps, allowing each to focus on a smaller problem, rather than trying to solve too many things all at once.

In particular, your highly effective use of the orthographic plans we explain here in the notes helped a lot with this, and from what I can see, you didn't spare any effort in pushing them to their limits. Very well done. Be sure to keep it up when tackling Lesson 7 as well, when you get there.

There's really only one issue of note that I want to call out. It's not really relevant to the core principles we're teaching, but it is an instruction that was mentioned, but one that you apparently missed. As noted in this section, where we give permission for students to use ballpoint pens (in fact we encourage it) for this lesson, I also stress the following:

don't switch pens to do any sort of "clean-up" pass - use the same pen through all your lines, including construction/box subdivision/etc

You appear to have done exactly that, switching pens to a darker one to trace back over your existing lines. This is absolutely not something you should be doing in this course. It causes us to focus on how those marks we're drawing exist as flat lines on the page, rather than as edges moving through 3D space, which takes us away from what these exercises all focus on. It's for this reason that even the use of line weight, as discussed here back in the 250 box challenge, doesn't focus on tracing back over the entirety of what we've drawn, but rather on adding sections of lines that get just a touch thicker to clarify how those overlapping marks should be organized, in terms of what's in front of what. If you've attempted to "ink" your own sketches in the past, this is also a common issue that arises - our sketches can feel energetic and full of interest, but then when we ink them, they get stiff, static, and boring.

Anyway! Keep that point in mind, but all in all, fantastic work. I'll go ahead and mark this lesson as complete.