bean bag covers?

[theinnocence.livejournal.com]

i'm moving and i'm losing a couch but gaining 3 bean bags "chairs"
my new living room will be having a very zen fluffy bohiemian look. no real furinture, just pillows and a low lying table.

question is, does anybody know how to make a sturdy bean bag chair cover?
is there a pattern of some sort? these bean bags are old and sort of not that attractive looking.
plus it would be nice to have them blend in more and what not.