Rockfish-- I have been getting a lot of stuff together to soon deposit into my pond. I was looking and found peepaw's post about "self feeding fish feeder" and on his website fishiding.com they sell this. it's a big net full of recylced plastics. They are $50, ouch! To simulate i have been melting 2 liters and milk jugs and attaching them to cut up milk crates. The crate panels are a foot or so square then 3 or 4 are ziptied together. I'm trying to make sort of an artificial reef of sorts that will be attached vertically to a fence that is in the pond. It allows for access from either side, holes big and small going through it. The heat gun puts a nice surface on the plastic that I think will support life. It also melts it down putting various holes in it. Seems to also make the plastic more durable. I have also melted some down and used zipties to put them all together by either melting or drilling a hole near that top opening of the bottle. I think it kind of resembles a riprap or rocks.

If I were you i would take all those bottles that you have available and make it happen!! If you have a harbor freight nearby you can get the heat gun for less than 10 bucks and the zip ties for a buck.