What you have there is a fine example of a hand turned wooden funnel!
Those templates are used to shape the outside rim into star shapes, hexagons ect.. The real trick is you really have to be on the centerline. Take a square (or round) blank and find the center. That template is best if spray glued right to the wood so it can't move (I have used a glue stick to be honest) Now line up that arrow with your center point and cut the shape out that the pattern makes. Now the best way to turn these is with a nice square blank (thickness wise) as a "tree bowl blank" is hard to get a nice centered pattern. Basicly said, store bought blanks are your best bet (or nice 12/4 lumber)
The blank is also best mounted with a face plate, say you have a 3" face plate, use a caliper to draw a 3" circle using your arrow center point as pivot and line it up that way. If you are off center, the pattern will be lop sided.
Next, is a tip. try to envision the bowl "stuck thru" a board and see if you can center the wing in the middle so that you have more of a suspension than a lip on the bowl. Bill Grumbine has a great video on doing these and both of his videos are greatly helpfull [
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