Almost all standard coffee makers require a coffee filter. However, this doesn't mean that running out of shop-bought paper filters should keep you from brewing your morning coffee. Homemade filters, made of either lint-free cloth or paper, work well at a pinch. Cloth filters can even be reused, if necessary.
Paper towel filters
When filtering coffee using paper towels or a sheet of kitchen roll, it's best to use plain, white towels. Tear off two full-sized paper towels and double them over at the joint. Centre the paper towels over the filter basket, then press down. Poke around the inside of the filter basket to make sure that the towels completely line it. Trim away any excess paper that sticks up above the rim of the basket. Fill the basket with coffee and slide it into place. Make sure that the basket fits easily into its compartment. This technique does not work well with other types of common paper products, such as napkins and toilet paper. That's because these items aren't designed to hold up as well to moisture.
Using a homemade cloth filter is a great way to cut down on waste. It's best to use a tightly woven, white cotton fabric, such as a clean handkerchief or square cut from a tea towel. Fold the cloth into quarters, then press it down into the filter basket. Either trim away or fold over any material that extends above the upper edges of the basket. Hand wash the cloth filter between each use, but don't use any washing-up liquid or washing powder. Residue can creep into your next batch of coffee.
Tights or stocking filters
Filters made from a new pair of tights or a stocking are great for cone-shaped filter baskets that you pour hot water into. They are not ideal for electric coffee pots, as the heat can melt the nylon. Cut off the tights or stocking at the ankle and insert the toe into the basket. Fully line the basket with the material, then fold the excess over the sides of the filter basket. Fill the basket with coffee, then pour hot water over the coffee and let it seep into a cup. Dispose of the tights or stocking after use.