I agree with all of the above. This is a bad idea. To answer some of you specific questions:

Originally Posted By Monica Heel
...How would pvc pipe work as a bear canister?


Terribly

Originally Posted By Monica Heel
...Is pvc strong enough?


Not if it is a small diameter and if it is a large diameter then end caps will not be strong enough

Originally Posted By Monica Heel
...Does a bear canister have to be odor proof?


No. A bears sense of smell is greater than a blood hounds. Hiding the smell of food from a bear is like hiding the smell of drugs from the TSA dogs on the border. It doesn't work.

Originally Posted By Monica Heel
...Any other possible ideas for a diy canister?
Thanks.


As others mentioned DIY most likely will be heavier than commercial products; it probably won't work; and it will not be compliant with regulations. If bear bag hanging is legal where you hike, you can do that DIY.