dear friends

this is my firts post

i just received 100 used lab cages from a friend, all of them without water bootles.

i am using dishes inside the cages and it is a mess!

i look on old posts for some info about waterers but i cant find exactly what i want.
so i came ask your help.

1) does anyone knows how to make homemade waterers from plastic pet soda bottle, like 1 liter coka or pepsi bootles and so on?
i heard that is possible but i cant figure wich kind of cork (drilled?), tube (inox?) or tube point (moving ball or tiny hole) i must use in a homemade project

2) can anyone put a link showing a gravity valve used in automatic gravity systems?
i don want to use this system now but i think i will use it in the future so i want to know exactly what kind of valve is used and if is possible to use plastic valves since one hundred of metal valves is too expensive.

tks a lot

ama