Cushions are for sitting, so there is no need to use such a good filler. Fiber cotton is a better choice. On the one hand, it is cheaper and has better softness and elasticity. Sitting on it feels comfortable, but it may not be very flat. After a long time to dry, you can basically continue to use it. Sponges can also be used. The shape is good, and it sits flat, but it will become thinner and break easily after a long time.