So apparently I never got notifications for this thread. And yes, I do realize its been almost 5 years. But I've revisited the chainmail hacky sack, so I thought I would share. First I'll answer the question j_betts asked about what I filled it with - it is filled with a fleece fabric.
I recently redesigned it a bit, and made it possible to weave with only one ring size. You can read about it here:
How to Make a Chainmail Hacky Sack