If you have more doorstop covers than you do inserts, these waterproof-lined, 4″ cotton-bound inserts should do the trick of giving them some structure. Filled with uncooked rice and weighing 1kg, they’re just about out of the way enough to not cause injury while still keeping your doors open. But if you’re needing a doorstop that comes with both cover and insert, then you can find them here.