oh and you don't want a circular piece of material to make a cone
Big triangle, sew down long side
Don't like the sound of a big wooden ball. Sounds hurty, particularly on fire, and prone to, um, burning and falling to bits.
A really tightly crumpled ball of tinfoil would probably work well, maybe something else or a bit more weight inside it. But it'd be cheap, wouldn't get damaged and wouldn't get very hot either.
i was playing with other peoples aerotech socks at synergy
three different pairs and they were all lovely