Crochet a granny square for a Papemelroti postcard

I have already made knitted postcards so I had this other idea. Why not make a postcard with a granny square since the Papemelroti blank postcards are squares.

I followed the pattern in here and then added a few more rows. 

I then attached it to the postcards with chains. I just made chains and single crochets. And I was able to make something like this. 

Honestly this is way easier than a knitted postcard.

I also made other granny squares....