The fact that you weren't able to get an ellipse guide prior to starting this challenge definitely put you at a disadvantage in a number of cases. Ellipses are of course notoriously difficult, and in order to really get them down consistently, students will generally need to have had considerably more experience and mileage with them than they would have by this point in the course. It's not that ellipses are mechanically impossible to draw freehand - it's just that it's one of those things that reminds us that we're still beginners, that this is just teaching us how to continue practicing and refining our skills.

So, I hope that you are able to get your hands on an ellipse guide. Often students will go a quick search and immediately see really high price tags for full sets of ellipse guides. Instead of selling your kidney to get one of those, I generally recommend that students look at "master ellipse templates", which consists of a single sheet with ellipses of varying degrees, but limited to smaller sizes. It does limit how large you'll be able to draw those ellipses, but most students have been able to make do with them. This is something I mention back in Lesson 0.

Onto your critique. I'm going to largely ignore the issues that come from freehanding your ellipses, and instead address issues where things could be approached differently to yield better results (rather than where you tried to do something, and simply weren't able to get the mark to fall in the right place).

I can definitely see that you're very mindful of various components of your constructions. Since you struggled with your larger ellipses, the placement of those ellipses were obviously off in a number of places, but the way you've tried to lay them out is largely correct, and you've paid attention to how the degree of your ellipses ought to shift as you slide along the length of a given wheel. You've also shown a great deal of care and patience in capturing the various features of the rims themselves, and in most of these did a great job of capturing those details without losing their structure/pattern. 14 was particularly complicated, and while things fall off a touch here and there, you still hold to that structure quite nicely and end up with a piece that feels believably three dimensional.

When it comes to tire treads, I did see one or two places - mostly #18 - where you tried drawing a chunkier tire tread. That is, where the tire tread actually comes off the surface with a pretty significant form of its own. Despite the fact that these are clearly solid and significant, because of how these forms rise off the surface of another object, they are still technically considered "texture" and therefore should be drawn by applying textural techniques rather than constructional ones. Specifically, we should be implying the presence of those textural chunks rather than drawing them explicitly. I go into detail as to what this means in lesson 2's section on implicit vs explicit drawing techniques, but I'll explain it in simple terms here:

• Explicit drawing is what we're usually familiar with. We outline the form we're drawing to define the space it occupies, we draw its edges (where the various surfaces of the form meet, if there are any sharp corners). You can think of it simply as drawing the object itself, along with all of its internal details/lines, including its own texture.

• Implicit drawing is where you don't actually draw the form itself. You draw the effect its presence has on the surfaces around it - for example, any bump or ridge or bit of form along a surface would cast a shadow onto its surroundings. This cast shadow exists as a very specific shape that itself outlines part of the form in question (though doesn't outline the whole thing). Additionally, the cast shadow is a shape which expands in multiple dimensions rather than a line which mostly follows a path while varying its thickness in a limited fashion. We don't draw any of the internal lines/details of the given form - we just imply where it exists, and by drawing the shadow shape it casts, can convey certain properties of its relationship with the surface upon which the shadow is being cast.

Again- make sure you revisit those notes in lesson 2's texture section to get a better grasp on these principles. In situations like this, where the forms are so big and notable, it can be confusing as to which technique should be applied. Just remember that texture is made up of forms that run along the surface of another object. Those textural forms might be big, but if you could reasonably cut the surface off the object and lay it out flat while maintaining the arrangement of those forms, then it's a texture.

This whole matter of implicit drawing techniques actually comes up with another one of your wheels - #8. Here when drawing the spokes of the rim, you tried to rely on filled shapes to give those spokes a greater sense of dimensionality. The attempt didn't quite come out right, and I'll explain why. Shadow shapes are an excellent tool, but they should be used (within the scope of the drawing we do in these lessons) for implicit drawing. What you did here was to fill in one of the side faces of these forms with solid black - meaning you drew on the form itself (explicitly), rather than using the filled black shape to represent a shadow that form was casting.

You can see the difference shown in this diagram. Notice how on the right side there, we capture how the form itself is three dimensional without actually filling it in - we don't need internal lines representing the edges between the faces, we're able to understand it as a 3D form purely by how its silhouette is drawn. The filled shadow shape is instead used as a cast shadow, and further emphasizes that silhouette, while also allowing us to get additional information on how that form relates to the surface on which it's sitting.

On the right side, it actually comes off a lot more flat, simply because our eyes read those filled shapes as though they're shadow shapes, leaving the form as just a single flat face. Our brain can't quite understand how this could result in that kind of shadow, and so it just feels a little off, and undermines the illusion that we're looking at something three dimensional.

This critique has already gotten pretty long, but there is one last thing I want to point out. When adding line weight, don't try and use it to replace or "clean up" a rough line. There are a number of cases where your ellipses were drawn quite roughly (for obvious reasons), but you traced back over them to provide a steadier line on which to hinge your construction.

The problem is that tracing back over a line in this manner focuses on how that line sits on the page itself as a flat entity - not how the mark we're drawing is meant to represent an edge in 3D space. In order to avoid this, every mark we draw should always be drawn using the ghosting method in order to both maintain control and keep things as tight as possible when drawing lines initially, and also so we don't get caught up in the trap of tracing over lines when adding line weight. Line weight itself should really instead be focused on clarifying specific overlaps between forms, and should be limited to specific sections of an existing line rather than replacing the whole thing.

So! I've laid out a number of things for you to keep in mind. I am going to mark this challenge as complete, as I am getting the impression that you're doing a good job with it despite the disadvantage at which you set yourself. Please be sure to try and grab an ellipse master template (again, these are much more reasonably priced when compared to a full set of ellipse guides), as they will help keep you from getting distracted when working on your vehicles, and will allow you to focus on the things that will actually require your attention. Vehicles are notoriously challenging, and you will need to bring all your focus, patience and tools to bear.