You just need to practice your aussie accent Dave. It rhymes . . .

I bought some foam sheet from QLD Air cleaners, and cut my own using the lid as a template. Heaps cheaper than buying anything genuine or aftermarket. I think the sheet was about 15 dollars and is 1m x 1m, so you could cut 1000 filters out of it.
Make sure you oil it though. I still run the lid on mine with extra holes drilled in the lid.
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