Flux Filters are a key component in Arcane Alembics and Require only a few ingredients.
Crafting[]
In an Infusion Altar. You will need 2 Gold Ingots and 1 Silverwood Log
In Addition[]
You will need 8 Permutatio and 8 Purus. Permutatio is found most readily in seeds and Purus is most easily found in Silverwood or refined iron unless you're not going to miss a few diamonds.