I use drinking straws, too, with good success and stability. I use one straw for every 1" diameter on the pan (8" cake gets 8 straws) and locate them just inside the edge of the cake they’ll support. I’ve not stacked larger than 10", but I’m guessing I’ll get paranoid and add a couple of more nearer the middle when I do. Jenniffer’s measuring & cutting technique is the one I use.
