Ch3mic4l Fact0ry, one Gr4ing3rs Rd. West F00tscray. This ones pretty hard to get into and seems to be getting ready for demolition, but who knows how long it will take them to demolish it. It's not a very large site compared to other ch3mic4l fact0ries out there. But there's lots of industrial equipment and largeish ch3mic4l storage silos. There's also a small double storey office block with: office, lunch, and toilet facilities on the bottom level, and lab space on the top floor.
If you're a good climber (which I'm not) you could also jump over the fence into a foundry which adjoins the ch3m fact0ry. It's a 6 or 7 metre drop down some racking and it's the foundry at two6zero Geel0ng Rd. West F00tscray (which appears to be vacant) and runs all the way back to meet up with the ch3m fact0ry.