Schaff has standard, thin, and extra thin temperament strips for a few dollars each. Why would someone not buy them?
Here's why I didn't: I was advised by Bill Bremmer not to buy Schaff's temperament strip. He said that they are not very durable. Instead, he suggested I buy some medium action cloth (item 317G). In terms of price, all of them are around $4.
I'm quite happy with the action cloth - it's certainly durable enough. It's rated at 2.8 mm, but because of its tight weave, it's a bit thick for closely-spaced unisons, especially if I want to use it in the bass. I might buy a strip of thin action cloth (317-1/2G) on my next order. That one is specced at 1.8 mm.
...Because it is *cloth*, not felt... Meaning, woven cloth is more durable than pressed felt. (That's a Schaff item number, right Mark?) It's great for muting the three-strings. It works on some bi-chord wound bass stings, too, but I agree, Mark, that thinner might do for some wound bass gaps. I've been having better luck just using rubber wedges on the bi-chords...
Here are some pictures of Bill using the cloth on the wires:
And speaking of wedges,
It would cost me more money in time than they cost to buy.
Hmm... Well I gusse I sould focus on what most techs have laying around their shop. I have some bellows cloth and gasket leather laying around from some work I did on a player piano. I was thinking make strips of leather back them with cloth then mayben add some felt on top of the leather or just use the leather alone.
I was thinking about doubling up some plumber's gasket, but wedges are so darned cheap to buy, why not just buy them? Even the ones with handles are cheap!!!