Guide curves provide us with much more flexibility when it comes to lofted features that we lack when applying the feature without them. Because of that, we will create the shape shown in the following diagram to learn about one way of using Guide Curves:

Let's go through our usual procedure of creating models: planning, sketching, and applying features. Our plan will be to create the two profiles and then create the four guidelines. After that, we will apply the lofted boss feature. Follow these steps to implement this plan: 

1. Create an extra plane by offsetting the front plane by 50 mm. Then, create the two circle profiles that are shown in the following diagram. The smaller diameter is 40 mm, while the larger one is 80 mm:

2. Using the right plane as a sketch plane, sketch the upper guide curve, as shown in the following diagram. Note that to fully define the sketch, the endpoints of the guide curve should have a Pierce Relation with the profile, as highlighted in the following diagram:

3. Mirror the first guide curve for the other side, as shown in the following diagram. We are doing this because the lower part of the curve is the same as the top one. Then, exit the sketch mode:

4. Now, let's apply the lofted boss feature. We will use all of the profiles and the guide sketches to apply it. Select the Lofted Boss command. Then, select the two circular profiles.
5. Under the guide curves section, select the two guide curves we created. Note that we created the two guide curves under one sketch. Hence, when selecting one curve from the canvas, we will see the window that's shown in the following screenshot. As we can see, we can select the Open Loop option and then click on the green checkmark to apply it:

Note that our loft will shift toward the guide curve.

6. Following the same procedure that we completed in Step 5, select the other guide curve. After that, our preview will look as follows:

7. Click on the green checkmark to apply the loft. The resulting model will be as follows:

Note that we have only applied two guide curves to govern the loft from the upper and lower sides. Hence, from the unguided side, we'll notice that the resulting shape is more elliptical. If we need more guidance when it comes to shape, we can increase the number of guide curves as we see fit. There is no limit to the number of profiles and guide curves we can have.

This concludes this section on lofted guide curves. We covered the following topics in this section:

• How to apply guide curves to control our loft
• How to select a part of a sketch and make it a guide curve

In this section, we covered the lofted boss and lofted cut features, how to apply them, and how to modify them. We also learned about guide curves.