Coffee can lid? What type of material? Not being smart....just that there are many brands and they all use different materials. I have never heard of this. Ive made revolver wads from a few materials; felt, paper towels, and rinsed and dried cotton fiber baby wipes (only one specific brand and type from this particular brand uses a thin cotton felt like material, i dry the sheets and cut into squares to use as cleaning and oiling gun patches. Works amazing and is innexpensive). I use the paper towel method to make hard thin wax lub disks and you can stack them to make a custom thickness of wad. Also as cards ive used all kinds of cardboard and cardstock but have now mainly used waxed paper plates...they dont allow the powder to be contaminated by lube if making paper cartridges or keeping a load in the cylinder for a long period of time. I also use them to top my paper cartridges that have no bullet..one side is waxed and the other is not so the side that is waxed i putput towards the lube disk and the side thats not gets the glue that seals the overlap of the paper cartridge