In the past I have made partitions from Lexan (perspex)... Lexan is good because you can cut and drill it with normal hand tools.. As long as the lexan and the tools you cut it with are free from oil band other contaminents, then there should not be any issues...
I have also used glass from old, leaky fish tanks for partitions..
I once bought a plastic peg basket like the one pictured below, and used the plastic mesh section as a tank partition on a smaller tank..
Go into Bunnings and have a walk around and see what you can find..