I made this rug from recycled grocery bags.  It really didn't take all that long to complete.  (Except for my procrastinating.)

Here is a close up view.

Take your bag and flatten it out.

Then fold it in half.

And in half again.

Then cut off the top and bottom.

Toss the top and bottom pieces and then fold your strip in half and cut it.

Cut each of these strips into four pieces

Now you have eight loops to work with.

I do several bags at once and then I have lots of strips to add as I crochet

Her is how you add loops to lengthen.

 I did a simple single crochet for the whole thing using a Size N hook.

Good luck.  Feel free to ask any questions.