see this link: http://www.pickles.no/puff-daddy-knitted-stool
42 stitch's in garter stitch, rectangle shape; stitch together both ends of the rectangle creating a cylinder then spool knit a cord to bind the sides leaving room on one side to stuff with the foamy materials (can also untie and re-stuff if the materials get flat) I asked my daughter Emily; she is 13 if she would be interested in a bean bag chair - she was very excited - I had her pick out colors from my yarn stash - because she is involved she is really looking forward to it being finished.
We are using hobby lobby yarn bee bouche traditions grape tones 2 ball skeins. I am doing my bean bag chair on the knifty knitter large yellow peg loom it has 41 pegs and I can seal the ends by using the hat brim flip over stitch and just put the spool cord through in the beginning of the knitting and close it when finished When I finish the knitting I will inside out the knitting so the garter stitch (Perl side) will be showing - also for the stuffing I read on the article you can use one of those new stretchy garbage bags in the bean bag chair and fill it with stuffing and that will prevent it from spilling out stuffing through use, wear and tear. I like that this bean bag chair will not need zippers and can be washed in the washing machine just by removing the plastic garbage bag inside it with the stuffing.
I advise a bulky yarn or double knit (using two balls of yarn at the same time) when you do this that way the white plastic bag holding the stuffing will not show no matter how many times it is jumped upon. - This can also be done with fabric and sewed by hand or machine doesn't have to be knitted or crocheted Have fun!