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In my son's room I wanted to make window coverings that matched his airplane themed room but wouldn't need to be remade if we changed the theme when he got a few years older.  Because as much as it pains me I know my baby won't be little forever. :(
I found these no sew roman shades and knew it would look great.  We had two rooms in the house that had one window with traditional blinds in them and no window coverings at all so I had to do something that would work with the stuff I had in the house as much as possible.  So I took the set of blinds out of the bathroom & installed them in the other window in Gabes room without blinds. 
Here's What You'll Need:
Cheap horizontal blinds
New pretty fabric
Fabric glue (find this at a craft store)

To begin you'll need to cut out all the ladder looking string on the blinds.  Make sure you don't cut anything else or you'll have ruined the blinds.
Next youll need to take the blinds apart.  Look on the bottom slat of the blinds and remove the two little pegs and untie the string on the outsides of the blinds. 
Next pull off the extra slats I chose to keep 4 slats to make even portions when the shades are up.
I laid it out on the floor for all of this to keep it even and just sorta eyeballed where each slat needs to be placed. 
Reattach the bottom of the blinds.
Next take your fabric and lay it over the slats and glue it to the underside of the top of the blinds, the slats in the middle and the bottom of the blinds as well.
Let it dry & your all done. You simply slide the blinds back into their place.

Side Note:
Make sure you glue the material to the BOTTOM of the top of the blinds.  You need to be able to see the string that hangs down to adjust the blinds.  See the first picture bellow.
Also if you look in the picture in the middel I added one of those little hooks that screw into the wall to hand the string on once the blind goes up. Since they are in my toddlers room I wanted to protect him.