One time I had to spread some paint and no brushes around and I had a good size scrap of carpet underlayment - (the old type that was a smooth foam not the newer chunky style). I flopped it over a strip and stapled it in on both sides. Not bad but no cigar. I get foam brushes and metal handle flux brushes at my local dollar store in packages of about 10 or so for $1. 1 1/2" chip brushes are .35. I know artists who use scraps of carpet folded in half. But after a while ????