Starting with your form intersections, it's at this lesson that this exercise really ends up showing its value. That is to say, when we assign it back in Lesson 2, it's really just to plant a seed - to give the student a task that will get the gears in their head turning. It plays an important role in that regard (although in the future we may reevaluate just how we handle this), but it definitely leaves a lot of students floundering, looking for explanations that simply won't make sense to them at that stage in the game. All we can do is give them some general information, and let them flail away.

Then, as they work through Lessons 3-5, they get more experience in thinking about how different forms can fit together and relate to one another in space - organic forms that aren't nearly as punishing as these clean-cut geometric forms - but it helps to develop their spatial reasoning skills to a point where, now, we can talk a little more about those intersections.

I'd say that you're at that point, but honestly you're somewhat further along. Your intersections here demonstrate a very well developing understanding of 3D space, and frankly I don't think you need additional help on that front. I will however give you this diagram anyway, just to help reinforce what you appear to already know, just in case it is beneficial. But, all in all, great work on this front.

Continuing onto your object constructions, you have similarly done a pretty good job here. This lesson focuses very much on the idea of precision. Lessons 3-5 have us working in an inside-out, reactive fashion, where we're never really wrong (as long as we're respecting the 3D nature of what we're building up). We may draw a ribcage too big, but that simply means our result is going to have a bigger chest, and that we may move other things out accordingly. But there's no clear separation between good/bad, or correct/incorrect, as long as you're following those principles of construction. Here, we take a different turn, and start to actually look at working from outside-in, planning things out and making decisions ahead of time.

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.

Overall you've done a pretty good job with this first major introduction to working with precision, although I do have some points to share that will help you push this even further. The first of these has to do with the orthographic plan we do in order to make all the decisions that will impact our construction.

If we look at this guitar as an example, there are a lot of decisions that have to be made at some point. Looking at the body of the guitar, it can be split into a top and a bottom, with the bottom being the really big portion, and the top being the smaller curve and the protruding bit, as shown here.

If we look here at your orthographic plan, you've established that the body as a whole takes up exactly one half of the guitar's overall height. You've also established the 1/4 mark, which seems to sit just a little ways into the "bottom" section of the guitar's body. But I can't see any specific information to figure out where exactly the border between the top/bottom sections is meant to fall. I can see that the upper half of the body (from 1/4 to 1/2) is split into 4's, but we do not know for a fact based on the information present that those are all equal.

If they are equal in size, then each of those sections would be 1/16th, so the blue line would be at 5/16ths.

But is it? That is entirely up to you, as you're doing the orthographic plan. In that sense, the plan isn't just observational - it's also where you make all of your decisions. The proportions you use for each landmark don't have to be perfectly accurate, but making those decisions here keeps you from having to make them on the fly, as you build up your construction in 3D space. It separates the process into stages, ensuring that all the information you need has already been determined, and that any potential conflicts (for example, you might decide the bottom of the body goes from 0 to 5/16ths but perhaps there's another element that could potentially also have been positioned at that point, so you need to decide where it's going to go) have been addressed.

That is really the main bit of advice I want to impart - don't just look at the big decisions, try to make decisions for as much as you can, down to the smallest points. Another similar thing you might overlook, for example, is looking at the ABXY buttons on your 3DS, you established the center of each button, but not how big each individual button would be, so there's no guarantee that those buttons are all the same size. Of course, you eyeballed/approximated it, but that's the point - we're trying to shift as much as we can away from approximation.

The last point I wanted to call out was just a quick reminder about these notes on how to deal with curves. I noticed that some curves - like in the body of the guitar, and the curve of the toilet - didn't apply what I'd explained there, about first establishing your curves as a chain of straight edges or flat faces, so do be sure to review it before moving on.

And with that, I'll go ahead and mark this lesson as complete.