This isn’t a tutorial because we’re not adobe illustrator pros. These are the steps we took to design a barbell in adobe illustrator CS3 while experimenting with the program’s 3D revolve feature.
Step 1:
We drew a partial outline of half a barbell using the pencil tool as shown below:

Step 2:
We went to the “Select” tab and hit Select->All then we went to the “Effect” tab and hit 3D->Revolve to open the 3D Revolve Options dialog box as shown below:

Step 3:
While in the 3D Revolve Options dialog box we checked “Preview” in order to preview any changes made based on options we selected. We then elected to add “New Light” by clicking on the button indicated by red arrow in the example shot below (If you can’t see anything under “Surface Plastic” it means some of your options a hidden. You need to click the “More Options” button under “Map Art”)

Step 4:
We then clicked “OK” to apply the 3D revolve option. After the dialog box closed we mirrored the selection by clicking the middle anchor point and pulling it to the flip side as show in the images below:

Illustrator then completes the process of creating the 3D shape leaving us with a single barbell which we then exported to photoshop and flipped verticallyby going to Edit->Transform->Flip Vertical. It’s not the sexiest barbell ever designed but we’re beginners. We’re just trying to get practice.
Here’s the finished barbell:
