I hadn't thought about that.
I have heard of Mr. Goodman's kits. I was just kind of thinking of this as a diy project to keep me busy for a day or so.
I did think of a solution, though. I have some of those foam paint "brushes" and those are open cell foam. I can cut a tiny slice off with an exacto knife and see how that compares. I think it should work.
Just wanted to make sure that I don't have to get it perfect. Foam is kind of difficult to measure accurately with a pair of calipers.