I have received some questions about which batting that should be used for the boobs, and here’s what I suggest:
I use a thin, flat, rather firm polyester batting (which goes by the name of “table batting” here) myself.
Light (not dark) and washed fleece or flannel will probably be fine, and also firm needle punched cotton or polyester/cotton blends. If you’re not sure, try rubbing it with a cloth to see if it beards a lot. If it doesn’t, use it.
The reason why I don’t want batting that beards is that the raw edges are exposed and fluffy stuff all over the boobs will not look that great.
So, try what you already have at home – and go ahead - make some boobs.