Starting with your form intersections, your work here is overall very well done, with just a few minor points to raise. To be entirely clear though, this means you're doing better than expected. We introduce this exercise in Lesson 2, but only for that very purpose - to introduce it. The specific skills it hinges upon are the same skills this course as a whole seeks to develop, and which we delve into more deeply with the constructional drawing "puzzles" we encounter between lessons 3 and 5. So we can think of its inclusion in this lesson as being an opportunity to see how students are now rolling with this particular distilled form of the overall topic of the course, to identify any issues and provide further information that can now be better leveraged by the student given their increased experience. It is at this point pretty normal to see students being far more comfortable with intersections involving flat surfaces, but to continue to struggle with those involving rounded surfaces.

In your case however, you're actually fairly comfortable with the latter as well, although there are some minor points I want to call out, which I've noted here on this page. Starting with the cylinder-cylinder intersection, this one was mostly correct, but the actual curvature of the sides of the intersection line weren't curving dramatically enough to continually follow the given surface. It helps a great deal to take specific note about how the surfaces at play are curving, as when we jump straight to thinking of the whole intersection line as a single entity, it becomes easier to blend them together, resulting in a muddier, less distinctly correct intersection - like what I showed towards the bottom left with the cylinder-sphere intersection. Lastly, the pyramid-sphere intersection towards the bottom right was the only case I noticed where the intersection line itself was actually incorrect - you had your curves inverted.

Continuing onto your object constructions, I can happily inform you that despite your uncertainty, you did a fantastic job in deciding how far to push your orthographic plans. While I certainly agree that new demonstrations would help immensely in getting these concepts across, they are planned but still very far off as we are still updating the video/demo material towards the beginning of the course for that same purpose. In essence, the course is always evolving and being refined, primarily based on what trends and patterns we see from students in their submissions for official critique. While we can clarify those issues for students as part of their feedback (so while certain things could be clearer in the material, in the interim we're still catching those issues for students and explaining them as part of their critiques to ensure that they are still getting the whole picture), it's those students outside of the official critique track who are ultimately left waiting longer before those adjustments trickle up to the lesson material. It would of course be ideal to have all of the material updated, but given our limited resources being primarily focused on those official critiques, we can only progress so quickly on that front.

But as I noted, in your case it does appear that the existing material was able to get the point across sufficiently, as your work here holds very strongly to the lesson's emphasis on the concept of precision. 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, and by extension, our orthographic plans. 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. When it comes to deciding "how much" subdivision we need to do, it ultimately comes down to the fact that we specifically do not want to use any guesswork or estimation. Everything we translate into our 3D construction, we want to have decided upon as part of our orthographic plan.

This is why you felt confused - you were looking for a cut off point, but the only one that exists is determined by how far we believe the construction should be taken. Arguably it would still be "okay" (debatably) to limit this lighter to just a box for the main body, a smaller box in the upper-left, a cylinder for the spark wheel, and call it a day. It wouldn't be nearly as detailed as it could be, but what matters are decisions made and decisions upheld. It would certainly be considerably less valuable as an exercise, but for the purposes of the concept this lesson focuses upon, it would be adequate.

It is then worth asking, "what if I do my orthographic plan, then while constructing the 3D structure I realize I forgot something?"

There are a few ways in which one might handle this, and they all sit on a spectrum of better to worse. On the better side would be simply going back to your orthographic plan, making the new decisions there by adding those additional subdivisions to update the plan, and then applying them to your construction. In the middle would be taking a step back, deciding what proportional relationships this new element needs, and pursuing those subdivisions right on the 3D construction (without going back to the orthogrpahic plan). And to the "worse" end would be simply adding the element by eye without first defining your desired decision in any way. Basically just jumping from idea to execution.

Despite your confusion, you held to the instructions very well, and ultimately came to the correct conclusion. Because the instructions didn't define a "far enough" point, you focused on applying what instructions there were to the best of your current ability, and never defined such a cut-off.

Not only does this mean you did a great job with this lesson and received the full benefit of its homework, but it also speaks to you approaching these conundrums in a manner that prioritizes discipline, that makes full use of the resources at your disposal, and avoids taking action that are not grounded in some fashion in those instructions. And of course, this is reflected strongly in your results and your growth over this course as a whole.

So! I'll go ahead and mark this lesson as complete. Keep up the fantastic work.