Jumping right in with your organic forms with contour curves, these are looking great. You're doing an excellent job of sticking to the characteristics of simple sausages, your contour curves are confident, smooth, even, and accurate, and you're also demonstrating a clear grasp of how the degree of those contour curves represents the orientation of each cross-sectional slice as the sausage turns through space.

Continuing onto your insect constructions, you are by and large on the right track here, but there are a few things I can offer to help ensure that you get the most out of these constructional drawing exercises. The first point I want to discuss is the importance of distinguishing between when we're engaging with our construction in three dimensions, and when we might be taking certain shortcuts that operate more in the two dimensions of the page itself.

Because we're drawing on a flat piece of paper, we have a lot of freedom to make whatever marks we choose - it just so happens that the majority of those marks will contradict the illusion you're trying to create and remind the viewer that they're just looking at a series of lines on a flat piece of paper. In order to avoid this and stick only to the marks that reinforce the illusion we're creating, we can force ourselves to adhere to certain rules as we build up our constructions. Rules that respect the solidity of our construction.

For example - once you've put a form down on the page, do not attempt to alter its silhouette. Its silhouette is just a shape on the page which represents the form we're drawing, but its connection to that form is entirely based on its current shape. If you change that shape, you won't alter the form it represents - you'll just break the connection, leaving yourself with a flat shape. We can see this most easily in this example of what happens when we cut back into the silhouette of a form.

I found this hercules beetle to have some good examples of this. In red I marked out where you cut into the silhouette of forms that were already present, and in blue I marked out where you attached flat shapes to an otherwise 3D structure, or used them to extend existing silhouettes out.

Instead, whenever we want to build upon our construction or change something, we can do so by introducing new 3D forms to the structure, and by establishing how those forms either connect or relate to what's already present in our 3D scene. We can do this either by defining the intersection between them with contour lines (like in lesson 2's form intersections exercise), or by wrapping the silhouette of the new form around the existing structure as shown here.

You can see this in practice in this beetle horn demo, as well as in this ant head demo. This whole premise is something I've been pushing more recently - so while it isn't as clearly represented in the lesson material yet (something I'm gradually updating, one step at a time), but you'll also find that the shrimp and lobster demos on the informal demos page demonstrate this as well.

Note in particular how every stage focuses on establishing the forms as solid and three dimensional before moving onto the next. This is all part of accepting that everything we draw is 3D, and therefore needs to be treated as such in order for the viewer to believe in that lie.

Continuing on, I noticed that you were generally making a concerted effort to build up your leg structures using the sausage method, although with some deviation at times, so I would still recommend that you review that linked diagram and note every specific element listed there. Most notably, I'm seeing a number of places where your sausage segments don't quite overlap correctly, and thus don't really have a clear intersection/joint to define with a contour line - all of which are important parts of the process.

Once in place, we can then build on top of this base structure with more additional forms as shown here, here, in this ant leg, and even here in the context of a dog's leg (because this technique is still to be used throughout the next lesson as well).

The last thing I wanted to quickly touch upon is how you're approaching the detail phase of these drawings. Right now you're largely focusing on pursuing "decoration" - that is, doing what you can to make your drawings more visually appealing, and often looking for reasons to add more ink onto the page (and sometimes slipping towards form shading, which is noted in Lesson 2 as something that should not play a role in our drawings for this course.

The problem with decoration is that it isn't that concrete of a goal - after all, there's no clear point at which one has added "enough" decoration.

What we're doing in this course can be broken into two distinct sections - construction and texture - and they both focus on the same concept. With construction we're communicating to the viewer what they need to know to understand how they might manipulate this object with their hands, were it in front of them. With texture, we're communicating to the viewer what they need to know to understand what it'd feel like to run their fingers over the object's various surfaces. Both of these focus on communicating three dimensional information. Both sections have specific jobs to accomplish, and none of it has to do with making the drawing look nice.

Instead of focusing on decoration, what we draw here comes down to what is actually physically present in our construction, just on a smaller scale. As discussed back in Lesson 2's texture section, we focus on each individual textural form, focusing on them one at a time and using the information present in the reference image to help identify and understand how every such textural form sits in 3D space, and how it relates within that space to its neighbours. Once we understand how the textural form sits in the world, we then design the appropriate shadow shape that it would cast on its surroundings. The shadow shape is important, because it's that specific shape which helps define the relationship between the form casting it, and the surface receiving it.

Note that instead of having us search for excuses to add more ink, this in fact works in the opposite way. We end up trying to convey all that we need to with as little ink as possible, making it a much clearer goal to strive towards.

Now, I've mentioned a number of points here but these are all things you can continue to work on into the next lesson. So, I'm going to go ahead and mark this one as complete.