Homebrew PCBs

I also agree that a milk bottle is the worst thing to store anything 
in. However, most milk bottles I've seen are #2 recycling, not #5. I 
have used FeCl, HCl + H2O2 mixtures, and acetone, in #2 and #5 
plastics (I find it interesting that when you buy pure acetone for 
woodworking, etc, it's in heavy metal cans with lids that are 
impossible to remove, but if you go to a beauty supply store, they 
sell pure acetone in #2 bottles with easily unscrewed caps. I've 
bought a few of these, and now refill them from a 1 gallon jug.). #2 
is what 2.5/5 gallon paint buckets are made out of. I think windshield 
wiper fluid is also sold in #2 bottles, which are heavier than the 
milk type. I use '13 qt sweater box' tupperware to etch in, which are 
#5. I recycle the FeCl3 with peroxide, which I've heard also creates 
CuCl in the mixture.

I was lucky not to have any FeCl leak when I used milk bottles to 
temporarily store it to take it to be disposed of. However, I put some 
water based varnish in one when the can it was in got damaged, and 
didn't swap it into a new can soon enough - the bottle got a dent, 
then leaked everywhere. Luckily nothing was damaged. Don't use milk 
bottles.