Creating the Digestive Tract

The digestive tract, or guts, consists of one long tube that you create by lathing a line.

Open Earthworm.max.

Create a line for the profile of the guts using all corner points by setting both Initial and Drag to Corner. Use a picture of earthworm anatomy for reference or refer to the image above. Name the line Guts.

If you need to adjust the position of any of the points, go to the Modify panel and choose the Vertex sub-object level.
Zoom in to the area that needs adjustment. Then select and move the points individually:

In the Name and Color rollout, rename the Line01 object to Guts.
Apply a Lathe modifier and choose the X direction. Set Segments to 8. Then click Sub-Object.

In the Front viewport, drag the axis of the modifier gizmo downward to make the digestive system wider:

Apply a MeshSmooth modifier, which is found in the More menu. The contours of the guts become smoother:

To fine-tune the profile further, go back down the Modifier stack to the line creation parameters and choose the Vertex level.
If you right-click on a vertex, you can change the vertex type to Bezier or Bezier Corner.
By dragging the Bezier handles, you can create smoother curves:

The final result should look similar to this:

Save your work as Earthworm01.max.

Next: Creating the Circulatory System