Introduction: Free Practice Canvas.
All you need to do to get free canvas to practice on is to keep your eyes open and be a little sneaky.
First you have to look around for old wedding, party, or yardsale signs that people forget to take down, Election signs, and sometimes you can find some signs from gas stations or fast food places, I got mine from a McDonalds
Second is to swipe them bring em home and cut them up into sizes you want
Paint them, they work great for practicing airbrush efects and just practicing painting.