I use coffee filters all the time in the bottom of my pots when I plant flowers. Lay several layers (2 or 3) of coffee filters in the bottom of the pot before putting the potting soil in the pot. The coffee filters hold the soil in while letting the water drain out through the hole. They do rot away pretty quickly, so I usually use 2 or 3 at a time. Too many more than that and they don't let the water drain well.
I love this idea with using the coffee filters for patchwork circles. Thanks!