Ok, so the picture has gone before the words. Not trying to confuse you, honestly, still getting to grips with this blogging malarkey….
Take two smaller sized cloths, with some kind of open weave. I used the muslin cloths available from pound/bargain shops to use with facial cleansers. I found them a little small for the intended purpose, but fine for this.
Using a paper coffee filter as a template, cut round the paper. You can cut it to this exact size. The paper filters are sealed at the edge, which will make them the same size once sewn. Straight stitch, by hand or machine around the sides and bottom of your material. I machine zig-zagged the top, to stop it unravelling, but you could give it a small enclosed hem instead.