Starting with the structural aspect of your challenge, you've done a good job in leveraging your ellipse guide effectively as you've built out each of these objects. I did however notice a few things I wanted to call out in terms of how you were approaching certain problems, which I've noted here.

• Firstly, on the top left, I noted that when drawing your wheels' spokes, you tend to have those structures' side planes continue on rather than being cut off where they intersect with the inner tube of the rims (as shown in the rough diagram I drew above, as well as on number 21). Without having the side plane cut off in this manner where appropriate, we end up undermining the solidity of the structure we're constructing.

• Secondly, for your bike wheel in 23, avoid drawing spoke structures with just a single line. It's simply that a single line does not convey enough information for us to understand how this structure exists in 3D space - it's not adequate for conveying the illusion of form. While it is no doubt more difficult, we at minimum would need to construct these thin strokes with two edges in order to enclose a silhouette.

• Lastly, on 22 I noticed that you were rather sloppy with the linework outside of the ellipses. While it is not uncommon for students to become lax when it comes to drawing shorter strokes - they'll often feel they can use their wrists for this, but as explained in these notes, whether the shoulder or wrist is used depends on what the stroke itself specifically requires. In this case, we're dealing with lines that need to be kept straight and consistent in their trajectory, so as to build out a solid structure - so executing these from the shoulder, using the ghosting method in order to maintain a confident execution would be necessary.

Continuing onto the textural aspect of this challenge, this exercise is honestly something of a trap. Being as far removed from Lesson 2's textural concepts, where we push the concept of implicit markmaking over explicit markmaking, and the importance of leveraging cast shadows to imply the presence of our textural forms, it is very common for students to forget all that and to simply charge forwards with whatever approach they feel best. It does appear you've fallen into that trap as well.

Fortunately it's not something I hold students back on, but it serves as a reminder that you will want to go back and ensure you haven't forgotten or lost touch with concepts we've raised earlier in the course. Generally we keep on top of such things by being sure to keep our warmups on a regular rotation so everything continues to be honed (as explained here in Lesson 0), but sometimes reminders are required.

In particular, I would recommend you review the reminders here as well as these notes on implicit markmaking - although going back over the whole section would certainly be beneficial.

I'll go ahead and mark this challenge as complete, but do be sure to review both the material pertaining to textures from Lesson 2, as well as the principles of markmaking and use of the ghosting method from Lesson 1.