I bought some meters of tyvek two years ago and I haven' t really worked with it since...It's an interesting material, looks and crumbles like paper and you can use it like fabric too. It is a nonwoven, waterproof material made of high-density polyethylene fibers. You can read all about it here.
I bought so many flowers for the balcony lately that I ran out of flowerpots. I decided to sew a flowerpot out of tyvek:
This is the result! I really don' t know why I used an orange frame here??!
It is not waterproof, because of the seam. For the balcony it' s sufficient anyway :)