sorry, but it's a trade secret! lol, not really. All i do, when i'm making a hollow form, let's take the tall elm one for instance. I mount it between centers, and rough out the shape. I go ahead and try and design it in 3rds, cause it looks better imo. So the top third, is the actual hollow form itself. I have to have a good idea what it's going to look like first. I then apply myself to the bottom 2/3, or, the leg portion. You can see in the pic, that i figured out where the top of the legs would be, and how i wanted them to curve inward and then flare back out towards the bottom.
Now that the leg area is rough turned, i then turn a tenon on the top of the hollow form, for my chuck to grab.(before turning the "orb") I then remove the tailstock from the lathe, and set up my steady rest. I mount the piece in the chuck, and mount the steady rest right at the bottom of the feet. Then I hollow out the leg area, while trying not to go too deep, or make it too thin or thick, and still keep to the curvature of the outside.
Once that is done, i turn the piece around, mount the bottom end in the chuck, and use the tailstock for the top. I then turn the outside of the hollow form part to whatever looks good (i hope). Then i remove the tailstock again, and install the steady rest around the hollow form, and begin to hollow it out.
After that? It's tough as nails. I draw my design as well as i can on the piece, and use whatever tools i can force to work, to cut out as much waste wood as i can. Then it's all chisels and dremels and die grinders and exacto knives, and many many hours of hand sanding. Did i mention hand sanding? Oh yeah, u must use sandpaper, for a long long time. (but it's a gr8 opportunity for me to sit back by the wood stove, and watch some documentaries out in the shop on the computer
When i first started turning, i got tired of sanding regular bowls, lol. Now, when I turn a big salad bowl, and it's done in a couple of hours, i'm thinking "Already done? that was easy!"
I've got about 15 hours at least in the elm piece. Probably more. It's so hard to carve!
Hope this answers your question.
With the smaller stuff, that don't have the center in it, like the clawfoot bowl, i merely made the chuck hole deeper, so that i would have wood enough for some type of legs.
It's a different way of looking at turning, for sure. You have to be able to envision a shape, and leave yourself enough wood to make it happen. Then stay committed, when your hands hurt, and your dremel is belching smoke, the die grinder is too hot to touch, etc haha. Good luck to anyone willing to try it, i look forward to seeing new pieces!
PS: I'm about to start a video series, this week, on youtube, of one of my creations, from start to finish. I'll let you folks know when i upload.