This is a great section of avocado tree trunk.  I have already cut it to length with a chain saw, and I have 8 sheet-metal screws screwed down through a metal faceplate securing it to the lathe.  I usually start with a roughing gouge to  cut the tree symmetrical.

In this picture I am roughing out the piece.  As I'm cutting the wood I'm thinking of what shape the tree wants to be.

As you can see, I've removed quite a bit of the wood.  The piece has taken form in my mind.  Now it's a matter of using the tools well, and a little luck.

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Now, I'm hollowing out the form.  I use a wonderful chisel designed by Dennis Stewart (that's the long tool lying across the lathe).  I start in the center and rough-out the piece going deeper and deeper.  I try not to get too thin yet.  The piece is just taking shape.

I wear an air respirator that has a battery pack (the blue square thing around my waist) to pump fresh air through a tube which ends up in my hard hat so I can breathe O.K.  The face shield has come in handy a few times.

Here you can see the form taking shape.  I use the large center steady to keep the piece from vibrating too much as it turns and is cut by the chisels.  It has  in-line roller wheels on the ends of the adjustable arms that ride on the piece as it turns.  These wheels help steady the piece, and keep it from shattering as it becomes thinner and more delicate.

A look at the piece after removing the center steady.

After I shape the top edge (I try to follow the grain of the wood) and the piece is as thin as I want, it's time to sand.  After sanding comes the finishing.  All of that is pretty boring to look at, so I'll stop here...