How would I make a makeshift flex wheel insert?

My team didn’t receive any flex wheel inserts, so we tried to make our own by cutting the fingers of intake rollers and then twisting them into the flex wheels, but after some time, they started to slip and wear away. So are there any other methods or ideas that we could use(possibly using some kind of insert with rubber bands to jam them into flex wheels)?

Please use forum search, this has been discussed many times before. One topic here.