I've read on here about replacing the polyfill in cartridges i was just wondering on my 510 cartridges if i could use the stuff from old cd sleeves i have a case for my cd's and a lot of the plastic is tearing.I started to throw it in the trash then i was looking at some of the pieces where the plastic had tore off and i was looking at the part the back of the cd is against and it looks like it might make a good replacement for the filler I was just wondering if anyone had tried this or if anyone with more experience than me thinks this would work.