2. The results looks like a glass, as you see on the left object. (change the ISOLINES system variable to 8 to give it a nicer look.) But when you use the HIDE command on it, as you see on the right object,

3. you see that it's a solid.

5. Here's the result, with some shading. Now, all you need is some water!

6. Draw a 3D threaded bolt I rummaged around a box of miscellaneous junk and found this bolt. You can see that it's about 3 inches long.

9. Note: Close the polyline ensures that you'll get a solid rather than a surface when you revolve. You'll need the solid for later operations, such as UNION.

18. Here's the result with the Framing Steel material. I expected it to be silver but it came out coppery. It looked so good that I left it.