If you use wipe on or rub in finishes like Dingo tone, Minwax, shellac, ink , stains etc, this might help you with making an applicator.
I was taught this by a guy who taught me French polishing.
Take a piece of lint free cloth, old T shirt works well, make a square about the size of a small handkerchief, this will be the outside layer of the applicator - the bit in contact with the finished surface.
Scrunch up some more and put it in the middle.
Tie it up and make like a Christmas pudding. Make sure that whatever you use for a tie doesn't dissolve or react with the finish you are using.