I used material from my stash to make these (she said smugly, inwardly congratulating herself for her thriftiness). Basically, I follow the instructions in Lotta Jansdottir's Simple Sewing for making pillowcases, but I don't bother using her pattern, instead I just cut around an existing pillowcase adding about 1.5 cm seam allowance and a 20 cm foldover on the back piece.
Now I have a question to ask you, if you don't mind. If you were going to a country fair, would you buy pillowcases like these? Or a robot? Or pillowcases and a robot? Or lemon and orange marmalade? Some friends and I are having a stall there, and although I love to make stuff I have always been a little shy about selling stuff I've made. I just don't know what folks will like, I guess.