Message in a Bottle USA only

Instead of putting that empty 16oz. water bottle in the recycle bin, fill it with goodies for your swap mate. Yes, the post office will send the water bottle - you just have to securely affix the address label, cost will be based on weight. Tape the cap on with packing tape, the post office must be able to see there is no liquid in the bottle. I have this as USA only to keep the costs down.
What to put in the bottle? whatever will fit - paper, beads, photos, ribbon etc - be creative. How will you decorate your bottle? The fun of this is only limited by your imagination. Have fun!!