I’ve been advised to use the crushed walnut shells, too - plus they add some weight to the pincushion which I personally like, polyester fiberfill just seems too light for me as I want my pincushions to stay where I put them. A lot depends on where you live - I have read that things like rice or sand can have a problem with moisture. Not sure but it does sound possible - perhaps in a really hot area with lots of moisture in the air could be a problem - but I also think that many/most of us have a/c in our homes. But we own my I’m-law’s home (my husband inherited it years ago) in way upstate NY (Gloversville, Fulton County) it does not have a/c. Personally I have trouble with that if I happen to be up there in the rotten times the area gets miserable (for me) to be there. Maybe that’s what people using steel wool might have a problem with - not a clue as I grew up in Phoenix and we never had a moisture problem!!!!
Sandy in Mooresville, NC