Too much worry thought about pincushion filler for me. LOL
I have more pins then I'll ever use so whatever is fine.

I've always used a scrap of white or tan wool for the batting and then stuffed with walnut shells. Worked out great for me.

I never thought about making pincushion as I had one cat that pulled pins out of the pincushion.
Been several years since he's been gone, still miss him.

To add to this discussion. I have used cheap kitty litter for my pin cushions with bags to hold thread snips!

I use Walnut Shells. Not only for the oils but because they naturally sharpen the pins and needles. I bought the last box I purchased online and paid $12-14 a box. I forget the weight but it is enough to last a very long time for the number of pin cushions I make.

I bought some emery grit from eBay. The bag ripped somehow and it’s all over the drawer it’s in. Supposed to sharpen the pins and needles. Hate it. Have also used the walnut shells ground up. Also didn’t like it. I collect antique metal pincushions and most of them need a new top. I used velvet. What I want are those raw wool fibers that shrink in warm water. They would have the lanolin they were talking about. My question is how long is the lanolin good for before it goes bad? And won’t the lanolin gum up my pins and needles?

Can't tell you how long the lanolin lasts but I've had my pincushions for
several years and they are still good. It's not going to gum up your pins and needles.
It's not like you're pouring oil in a pincushion. It won't make
your hands greasy.
It's just wool.https://cdn.quiltingboard.com/images/smilies/smile.png

I've used rice.

I use a mixture of walnut shells, batting and rice to weigh it down.

I took out the bag of sand that was in my cushion with hanging bag and replaced it with the square Zirkel magnetic pin cushion. It's heavy and the bag will not fall and it holds, pins, wonder clips, snips, and seam ripper while I'm sewing.