Making a small cigar sized wad in the bottom of a plastic sandwich bag and then rolling it up tight and rubber-banding it closed works pretty well! It has the advantage or being a soft shape that is easy to pack and easy to use as well!

I have also heat sealed it into short pieces of soda straw but that is a lot of work and even though it works well is not resealable in the field!! (It is waterproof which is nice!!)

Most of the other things that I have tried (35mm film can, small Nalgene bottle etc) where harder to pack not as compact or in the case of the film can the lid would pop off if you fell or rolled on it in your bag!

Oh I should add don't soak the cotton a little works better than a lot in this case!!

SD