You want those little nylon chip things they have in the paws and bottoms of sittable bears. They feel nice as well. Just wondering also if you baked your beans whether that would stop them germinating if washed.
You're right, best not put the sauce in as well . I'm not sure that mice would be especially attracted by essentially raw beans- they are poisonous after all. And baking them would not remove the toxin that's the poison.
You could always just buy cheap rubbers at The Works and shred them or chop them up. I think the trouble with this kind of product is that it's marketed at factories rather than individuals. You'll probably find a Chinese wholesaler out there willing to deliver you 5 tons or more.
I have a bag of plastic pellets bought 10 years ago that I use for the same purpose, trying to source a new bag as I am runing low, recommend tights for putting them in so they don't go through, tie or stitch up. Also recomend plastic milk bottle lids as a good flat base too.
OP - Sorry I didn't see your op earlier. I can get these from my suppliers if you need more. I bought 3 bags for a project I was doing last time I was there - I didn't think to buy them to sell - D'Oh.
To give you a clue on size of an 8oz bag, I think I'll need 2 for my doorstop if that helps.
If you need more and would like me to get you a price, please PM me, but give me plenty of notice as I only tend to order monthly.