For all who wanted info on the soda bottle targets, it's really quite simple. I just fill an empty soda bottle with commercial spray foam. Fill 'em up halfway and let em' dry/expand. 1 can of your average spray foam from the local home depot or hardware store seems to do about 4 bottle. Really makes for a nice, cheap target.
As far as their durability, well, they're no block or bag target. I got through about 1 every week or more. But that was a good solid week of shooting 3 dozen arrows (at least) a day; just hammering the things with field tips as well as hex heads, judo's, and my 160 Snuffers. Besides, after a while of shooting them in the middle, they usually break in two. This just gives ya' two targets that are even more demanding to shoot at. Excellent form of practice in my book...