Euro power strip clip for chair back

I need a powerstrip on the balcony to plug in 3 sets of Christmas lights. (Well, the outlets are too close together for the lights' wall warts, so I can only plug in 2 sets.) So I made this to clip the powerstrip onto the back of a wooden chair, to keep it dry and off the floor. Fits the kind of power strips that you can buy at Clas Ohlson in Norway.