Cutting shapes into our gun

To add detail (and enhance realism), we'll want to cut various shapes into the side of our gun. First, we want to create a circular cut-out in the middle of the body. Let's start by adding a circle in the Object model and lining it up where we'd like the cut to go:

Next, we're going to add a Shrinkwrap modifier to the circle. This is an incredibly powerful modifier to create cuts or recesses in mechanical parts.

We need to first select the name of our gun object in the Target box. Then, we'll need to set the mode to Project. Finally, we'll need to specify the axis that we'd like it to project on. In this case, it will be the X axis.

Once these settings are selected, you can drag the circle up against the gun, and it will conform to this shape.

Note

The more geometry (vertices/edges/faces) an object has, the better it will be able to conform to the shape of something else.

Let's pick our gun object again, and Tab back into Edit mode. We want to run a couple of loop cuts along the main body section. This will make it easier to fill in the shapes later:

Once we've done this, let's go ahead and apply the Shrinkwrap modifier to our circle. This will permanently change its shape and conform to the gun:

Next, we'll join the circle object to our gun by pressing Ctrl + J.

Let's delete the back faces here, so we can fill in our mesh:

This next part is a bit tricky. We'll need to fill in the spaces between the circle and the rest of our mesh.

I should mention that cutting shapes into curved objects is one of the hardest skills to master. There are several tools that can help you (such as Knife Project, which we'll look at momentarily), but they all have their limitations. At the end of the day, it really comes down to practice.

When filling in the curved areas of your mesh (such as this one), the general rule is this—Quads are preferable to Tris, and Tris are preferable to N-Gons. At the end of the day, it's the result that counts. If N-Gons work in a given scenario, don't avoid them just on principle.

As you go through this part, you'll probably find yourself needing to add loop cuts to the existing gun body. This is fine; go ahead and do it. More geometry tends to give you better definition, so don't be afraid to add some. As much as possible, we'd like our new geometry to follow the lines/curves of what was there before.

Here's what I ended up with:

It's not perfect, but this helps to illustrate the point. When we render this, it produces the following result:

This looks pretty good. There are no significant shading distortions around the curved areas, which is what we want.

Now, is it possible to smooth out the geometry so that it looks more appealing? Of course, but it's not necessary for rendering. A clean geometry generally produces better renders... but remember, the result is the ultimate determination of what is (and is not) a "good" mesh.

Before we move on to the next part of our project, it's worth taking a moment to examine the Knife Project tool. Its purpose is to cut shapes into existing objects; some readers will undoubtedly wonder why we didn't use it here.

Let's take a look.

To use the Knife Project tool, you simply need to add a circle object and line it up with where you wanted your cut to go.

Then, (in Object mode), you need to select your circle (the object that will do the cutting). Then, select your gun (the object that will be cut). Tab into Edit mode, and then press Knife Project under your Mesh Tools tab.

Here's what that will look like in our case:

Once we've removed the faces, we'll be left with this:

It looks pretty good, doesn't it? Nice and clean. So why don't we use it?

The problem is that Knife Project keeps the vertices of both objects. As you can see here, we've created a number of N-Gons along a curved surface and each of them have many vertices in close proximity to each other.

As we've seen before, this can have an adverse effect on shading.

You can see here that extra vertices create a few shading problems. Is it possible to fix these problems? Sure! You can join (merge) the vertices together and move them around until the shading looks good.

There's nothing wrong with Knife Project. Just like Subpision Surface modifier (we'll cover this later), this one is also a powerful modeling tool. Unfortunately, tools like these tend to be overused (particularly by beginners). This often prevents people from learning to manipulate and optimize meshes by hand.

So now, we're back here with our gun's body. Let's create a temporary N-Gon face to fill in our new circle.

Then, we'll use Inset tool by pressing the I key. This will extrude a new face towards the center, leaving a nice even border.

This is a key step, and it often gets overlooked. By adding the extra ring of edges (with the Inset tool), we preserve the shading around the edge of recessed areas.

Once we've got the ring, we'll again extrude the circular face towards the center of the gun.

As the face hits the center point of our gun object, the Mirror modifier will force it to become flat. Once this happens, delete the face, and you're left with a nice, cylindrical hole through the center of the gun's body.

If you'd like, you can now go through and add a little detail to it by beveling the edges.

Once this is done, the gun's body will look like this:

Next, we'll go ahead and add a cylinder in Object mode.

Tip

Adding Parts to Mirrored Objects

When using the Mirror modifier, it's often convenient to add parts in Object mode (versus adding them in Edit mode to the existing model). When Clipping is enabled on your Mirror modifier, you may accidentally distort your object if it's overlapping the center point.

Next, we'll scale and move the cylinder into position:

Using the and Inset Extrude and Inset tools, we'll create some basic shapes:

Then, we'll bevel our edges to add some detail. Once the cylinder's in position, you can go ahead and join it to the gun model by pressing Ctrl + J.

Next, let's select a ring of faces and duplicate it by pressing Shift + D. Then, we'll separate it to another object by pressing the P key.

Next, we're going to create some curved cooling fins on the gun. In order to do this, let's first run a series of loop cuts around these faces. This will enable us to use Proportional Editing to give a nice, curved shape to our fins.

Now that we've done this, let's turn Proportional Editing on at the bottom of our screen and select Sharp.

Then, we can rotate the middle ring of vertices, and we can scroll the mouse wheel to adjust the area of influence. Just rotate and adjust until you have given a nice shape to your circle.

Next, we'll select all other edge loops and push them back towards the center of the gun. Once we have the basic shape of our fins, we can go in there and bevel them. If you'd prefer, you can also delete a few rows of faces to create gaps or holes for heat to escape (this is not shown here).

The next thing we'll do is add a little circular detail to the outside of our recessed circular area. Start by placing the 3D cursor at the center of the circle. An easy way to do this is to pick a ring of edges and press Shift + S, Cursor to Selected.

Then, go ahead and add a cube.

Next, Tab into Edit mode on the cube and pull it up to the border of our circle. Using techniques already demonstrated, go ahead and add a bit of detail to it.

Next, ensure the cursor is still at the center of the circle. If it isn't, go ahead and put it there.

At the bottom of your screen, change the Pivot Point around which things rotate to 3D Cursor.

Then, select the entire geometry of the cube (in Edit mode), duplicate it, and rotate it by 180° around the X axis (press R, X, and 180 to do this). You will now have a cube at both the top and bottom of your circle. Select everything, duplicate it again, and rotate it by 90° around the X axis.

Repeat this process as desired, piding the angle in half each time. The math will break down as follows:

• 180°
• 90°
• 45°
• 5°
• 25°
• 625°

When you're finished, go ahead and join the object back to the main body of the gun.

Next, we'll add some circular cuts for screw holes. Start by adding a 16-sided circle to the scene:

Going into Edit mode on your circle and move it around until it's in a location where you'd like a screw/bolt to go. Duplicate the circle and repeat this until you're satisfied with the number/location of holes: