I found a kitchen item at Miller hardware that is a sifter with a stainless steel screen. I bout it for about $2.50. I used the screen in the baffle opening I made to attach a hose to send air to the heat muff and on to the cabin heat.
I cut a 1" hole in the baffle and riveted the 2 inch flange onto the back of the baffle with the screen between the flange and the baffle. I used red RTV to seal around the flange which stood off a bit because of the screen, which has a raised border, not allowing it to fit flush.
