Ok folk, here's what I came up with based on an amalgam of your ideas. Introducing the Super Tri-Star 3000! (R.I.P. Billy Mays)
First, draw an equilateral triangle on half a manilla folder (thin flexible plastic would be more durable, but I couldn't find any around the house), then bisect the sides.
Then, cut out the star shape, punch a hole in the center, and every 1/2 inch down each leg.
To use, apply to bowl with magnets or masking tape. Choose the holes you want to use to mount your legs and mark.
Bada bing, you're done.
Thanks again, all.