... for foam brushes when varnishing my kayak.  I had some open cell foam in a closet which I cut to manageable peices for tipping off after rolling on the varnish.  I recall that the foam cost about $14 for a chunk 72"x 36" x1"when I bought it for a cushion.  It seemed to behave just as well as the foam brushes which cost about 90 cents for a 3" brush.  I do have to use a brush, though when varnishing around the coaming.