I use templates all the time.Depending on how much I plan on using them I use cardboard or luan plywood.It will take a couple of practice pieces to come up with what you need.A circle cutter may also be a good option.HTH

We use a compass that came with our plasma cutter and it is adjustable to an infinite number of radii or diameters. It is a simple beam type compass that has a plasma torch holder with wheels (to hold the torch at the right height above the material) on one end of the beam and a magnet on the other end to hold the compass as you cut your circle out. We have fabricated them in the old days for the oxy/fuel torches. What we use our circle compasses for is to cut out beam penetrations in structural steel framing to allow mechanical trades to run their plumbing and electrical through the webs of deep section steel beams.
The other option is to buy a programmable plasma cutter that is simple to set up and program, these are fairly inexpensive compared to when they first came out on the market. Also, Check out "Bug-O" and maybe your plamsa torch mfg's websites and see what all they have to offer to help guide your torch around the radius you need.
Hope this gives you some direction in locating what you need,
John Wright

Hi Jeff,
I'm thinking that a template would be ideal.
Make another bowl, slightly bigger than the bowls you'll be producing, with a hole cut in the bottm that = desired hole dia + the thickness of your plasma torch head. Make sure that your template bowl fits snug around the sides but has a gap between the bottoms that allows the plasma operator room to partially insert the torch head. Now, with the bowl upside down, it's ready to cut. If the operator keeps the torch level while cutting, the hole will be within tolerance. If he wiggles the torch around too much, then you may have a problem. Depending on how may of these you need to cut, you could also make a jig that holds the torch in the correct position, in order to minimize rejects. With this setup, it will only take seconds to install the template and cut the hole, however, you will need to figure in time for cleaning the dross from the cut.

Good Luck
Tim

If you could email me your email address that will accept an attachment, I will send a couple pics I have taken of the two circle compasses we have purchased over the years and you could easily fab your own. First pic is of the circle compass for the manual oxy/fuel torch and second is a pic of the circle compass for the manual plasma torch. They are simple to set up and use.
1) Set the compass to the radius you desire and place the torch head in the holder.
2) You still have to adjust your cutting speed manually, but it guides your hand in a perfect circle.
John Wright

to answer your question of whether a plasma will cut the thin material you have is, "Yes". HVAC guys use cnc plasma tables to cut out the ductwork, they make all of their own fittings from flat sheets.

Thanks for your help guys,
It sound like the plasma cutter with a circle template would perform the desired cut out of the bowl base.
The bowl also has several fastener holes ranging from 3/16" to 3/8" diameter that are currently drilled out. We go through a lot of drill bits in this task. Is it possible that the plasma cutter could cut these drilled holes? What is the smallest hole size a plasma cutter could reasonably cut?

Thanks,
Jeff in Florida