Free (to me) Headboard

I love all the designs for DIY headboards out there.  Some are very simple.  And while there are plenty of cheap options, I needed something free.  We've never had a headboard since we've been married and I was d.o.n.e.
All I used was leftover moving boxes (yay free cardboard) and a leftover drop cloth. Obviously you can do one with wood, or a piece of foam board.  If you don't have a large piece of fabric that would also cost some money, but you can use an old sheet or something to cut costs.
After figuring out what size I wanted, I layed a bunch of cardboard pieces together.  Using spray adhesive I then added another layer (making sure seams didn't line up).  I did several layers of this until I had a pretty secure piece of cardboard.  I then covered it with my drop cloth.  Badda bing.  Free.  Sorry for no step by step pictures, I actually made this 6 months ago. It's so simple, I know you can figure it out.  Just make sure where the cardboard bends and edges don't meet up the same place every time.

To have a good tutorial (only using wood) I recommend this one, here.
To hang it I made a cardboard version of a french cleat.  I hot glued two long thin strips of cardboard (extra thick and sturdy) on top of each other.  I then rested those on screws that I screwed into the studs behind our bed.  It was sure nice to have that extra padding behind my head for all those nights of nursing in bed!