The store bought pads I've purchased are 1/4" polyester felt pads.
https://scubacompressor.com/?search_in= ... =felt+pads
So if you're going to cut your own I suppose you could get the same material and thickness from Mc Master Carr and cut to fit your cartridge/filter housing.
https://www.mcmaster.com/filters/materi ... ster-felt/
Good luck and keep us posted.
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