RE: Free advice from lawyers?
If you're selling this product, for profit or not, you might want to look into forming an LLC (Limited liability corp.) It's relatively simple and inexpensive to do, It doesn't matter if it's only a one person corporation (you), if my understanding is correct, your liability is limited to the holdings and property of the corporation (i.e. someone can't sue you for your house and your car if your product causes some injury, etc.). Oops - I just re-read, not sure if there is a similar entity in Canada. May be worth looking into though, esp. if you're selling to people other than close personal acquaintances. Maybe even then.
-J