Starting with the form intersections, I've noted some corrections to your intersection lines here. The issues I marked out fall into two main categories:

  • Cases where you were pretty close, but where the angles at which sections of intersections were drawn (like when crossing an edge, which results in a significant shift in trajectory that can result in a more dramatic change in angle than you've been drawing here. We can see this in the pyramid-box intersection at the bottom right of the page. For the cylinder-cylinder intersection on the bottom left, you were very much on the right track here as well, but the specifics of how that intersection is drawn would result in the intersection sinking into the volume of the lower cylinder, rather than remaining along its surface.

  • Cases where you may have been relying more on a sort of memorization (where we think in terms of, okay this form is "curved" and that form is "flat" so this is how we handle an intersection between one curved and one flat form) rather than actually focusing on the specific nature of each individual surface at play. A cylinder, for example, features ends that are flat (and therefore they engage in intersection similarly to a box). Across their length however, they are curved in one direction (wrapping around the shaft of the cylinder) and straight in the other (going lengthwise from end to end), so this means that we have to focus on the specifics of that intersection and the angles at which the different forms/surfaces are intersecting. Always keep in mind that the individual segments of our intersections occur between different pairs of surfaces, not whole forms.

In addition, I wanted to note that you did not draw through your boxes, and that your cylinders are drawn with length-wise vanishing points forced to infinity (resulting in side edges being parallel on the page). This suggests to me that you're forgetting important points from earlier in the course. While I imagine not drawing through your boxes was a simple lapse, you can refer to these notes from the 250 cylinder challenge for an explanation as to why forcing those vanishing points to infinity would be incorrect.

Continuing on, both your cylinders in boxes and your form intersection vehicles are coming along well (although you should definitely be constructing those cylinders around a central minor axis line to help with aligning your ellipses, as you did in the form intersections exercise itself).

One of the main reasons we assign the form intersection vehicles is to serve as a reminder to students that ultimately what we're building up in our more detailed vehicle constructions, though they may seem a lot more like individual lines and edges being laid out in space, then stitched together into a final object in the last steps, is still a matter of thinking in terms of building up from simple primitive structures to more complex ones. One can think of it like carving a piece of wood into a sculpture, where we start out with something big and simple, and slowly break it down, just as we do with the constructions involving more organic structures from the earlier lessons.

This is one area in which your vehicle constructions, though they absolutely demonstrate a well developing overall understanding of 3D space, and come out feeling very solid, do suffer a little - at least, in terms of the exercise itself, as one focusing on developing 3D spatial reasoning skills, rather than one intended to simply provide a good looking result. That is to say, everything we're doing here is ultimately an exercise, rather than a formula for how to draw, with the intention always being focused on what is going to have the greatest impact on your underlying, subconscious understanding of 3D space. So while your results are very nice, following the points I offer will be more about being able to continue building upon and improving that going forward in your own practice.

So the first point, I already mentioned - when building up your constructions, be sure to always think in terms of the primitive forms you're placing in space. If we look at this upper section of your moped, we see that you definitely skipped over a lot of those steps, and instead of building them up bit by bit, you appear to have relied more on your existing 3D spatial reasoning skills in combination with observing your reference. Outside of this course, that's great - but here we want to always go through the process of building up to it so your brain is forced to "solve the puzzle" and figure out how all the different components relate to one another in 3D space.

The second point is in regards to your use of orthographic plans. Right now they're very loose. Rather than identifying specific and clear landmarks and where they fall proportionally in each dimension, you did a very basic subdivision of the overall bounding box that didn't specifically identify the landmarks you'd want to know. This explanation back in Lesson 6, which is also referenced here in the material for this lesson stress this quite a bit. It was also raised in regards to your Lesson 6 work, although there you did end up applying the methodology more correctly in your later constructions.

I understand that you've been progressing through this course at a gradual pace, likely resulting in wide gaps between lessons, but it is entirely your responsibility to ensure that those gaps do not result in points that were raised to you previously not being applied later on. That means going back through the feedback you'd received, and going back through past lesson material thoroughly to ensure you're always moving forwards, rather than taking steps back.

Now, while that aspect of your work here is a little disappointing in that you certainly would have gained much more from these exercises had you implemented those points this time around, I am still going to be marking this lesson as complete. I believe that the issue comes down not to a lack of understanding, but a lack of thoroughness in how you opted to deal with the larger gaps between lessons. That is something you can address yourself.

While it may be a little anticlimactic as a result, you have still achieved something quite considerable in getting through all of the core lesson and challenges of the course - so congratulations. Just be sure when moving onto other courses, that you always take it upon yourself to apply the material you're given as effectively as you can, making choices towards that end. You put a lot of valuable time and effort into these things, so doing everything in your power to maximize the return you get on it is in your best interest.